Terminal device, monitoring method, and integrated circuit

ABSTRACT

A terminal device is configured to monitor a radio link on the basis of a specific threshold value defined as a level of a downlink radio link and the threshold value is defined by taking into account the number of repetitive transmissions and/or repetitive receptions.

TECHNICAL FIELD

The present invention relates to a radio communication system, a basestation device, and a terminal device, and more particularly relates toa terminal device, a monitoring method, and an integrated circuit whichrelate to control of data transmission and reception.

The present application claims priority based on Japanese PatentApplication No. 2015-001939 filed on Jan. 8, 2015, the contents of whichare incorporated herein by reference.

BACKGROUND ART

Under the 3rd Generation Partnership Project (3GPP), the W-CDMA schemehas been standardized as a third generation cellular mobilecommunication scheme, and is currently in service. HSDPA, which has evenhigher communication speeds, has also been standardized and is currentlyin service.

Meanwhile, under the 3GPP, the evolution of third generation radioaccess (Long Term Evolution: LTE or Evolved Universal Terrestrial RadioAccess: EUTRA) has also been standardized, and LTE service has begun.The orthogonal frequency division multiplexing (OFDM) scheme, which isrobust against multipath interference and suited for high-speedtransmission, has been adopted as an LTE downlink communication scheme.Furthermore, considerations pertaining to cost and power consumption ofterminal devices have led to the adoption of the discrete Fouriertransform (DFT)-spread OFDM scheme based on the single-carrier frequencydivision multiple access (SC-FDMA) that allows for a reduction in thepeak to average power ratio (PAPR) of transmit signals, as an uplinkcommunication scheme.

Additionally, under the 3GPP, discussions about LTE-Advanced (orAdvanced-EUTRA), which represents further evolution of LTE, are ongoing.In the LTE-Advanced, it is envisaged to use bands having a maximumbandwidth of up to 100 MHz for each of uplink and downlink, to carry outcommunication at maximum transfer rates of 1 Gbps or more for downlink,and 500 Mbps or more for uplink.

In the LTE-Advanced, it is contemplated to achieve a band of a maximumof 100 MHz by binding together multiple bands which are compatible withLTE, so as to be able to accommodate LTE terminal devices as well. Notethat in the LTE-Advanced, a single LTE band of 20 MHz or narrower iscalled a component carrier (CC). A component carrier is also called acell. Binding together bands of 20 MHz or narrower is termed carrieraggregation (CA) (NPL 1).

Meanwhile, in the LTE-Advanced, issues relating to lowering the cost ofterminal devices that correspond to specific categories, such as machinetype communication (MTC) or machine type communication (M2M), are alsounder examination (NPL 2). Hereinbelow, MTC/M2M terminal devices, orMTC/M2M communication devices will also be referred to as a machine typecommunication user equipment (MTCUE).

In order to realize low-cost MTCUE while maintaining backwardcompatibility with systems compliant with the LTE standard andLTE-Advanced standard, cost reduction methods have been proposed, forexample, by narrowing the transmission/reception bandwidth, reducing thenumber of antenna ports/number of RF chains, lowering thetransmission/reception data transfer rate, adopting a half-duplexfrequency division duplex scheme, reducing the transmit/receive power,and extending the discontinuous reception interval. It has also beenproposed that reducing the maximum bandwidth of MTCUEtransmission/reception RF circuit or transmission/reception basebandcircuit would be effective as a method for realizing low-cost MTCUE.

In MTC, cost reductions are not the only issue being studied, andcoverage enhancement for enhancing the transmission/reception range ofMTCUE is also currently a subject of study. In order to enhancecoverage, it is contemplated for a base station device to repeatedlytransmit downlink data or a downlink signal to MTCUE, and for MTCUE torepeatedly transmit uplink data or an uplink signal to the base stationdevice (NPL 3).

For example, the base station device repeatedly transmits multiple timesa physical broadcast channel PBCH to the MTCUE within 40 ms. Also, in arandom access procedure, the MTCUE repeatedly transmits the same randomaccess preamble, using multiple resources of a random access channelPRACH. Having received the random access preamble, the base stationdevice repeatedly transmits a random access response message. Note thatthe base station device notifies MTCUE within a cell through a broadcastchannel BCH, or individually notifies MTCUE, of the number ofrepetitions (or a parameter associated with the number of repetitions(also termed the repetition level, cell enhancement level, or the like)(NPL 3).

For example, the number of transmission repetitions of random accesspreamble or the number of transmission repetitions of random accessresponse message is notified through the broadcast channel BCH. Anothertopic of ongoing study is how to enable MTCUE to select a single numberof transmission repetitions from among multiple different numbers oftransmission repetitions, where the numbers of transmission repetitionsof random access preambles include multiple different numbers oftransmission repetitions.

CITATION LIST Non-Patent Document

[NON-PATENT DOCUMENT 1] NPL 1: 3GPP TS (Technical Specification) 36.300,V11.5.0 (2013-03), Evolved Universal Terrestrial Radio Access (E-UTRA)and Evolved Universal Terrestrial Radio Access Network (E-UTRAN),Overall description Stage 2

[NON-PATENT DOCUMENT 2] NPL 2: 3GPP TR (Technical Report) 36.888,V12.0.0 (2013-06), Study on provision of low-cost Machine-TypeCommunications (MTC) User Equipments (UEs) based on LTE (release 12)

[NON-PATENT DOCUMENT 3] NPL 3: “Rel-12 agreements for MTC”, R1-143784,3GPP TSG-RAN WG1 Meeting #78bis, Ljubljana, Slovenia, 6-10 Oct. 2014

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, with repetitive transmission (or reception) of data, when thenumber of repetitions is too great, each transmission/reception takesconsiderable time. Also, when the number of repetitions is too small, itwill lead to a deterioration in transmission/reception quality. In orderto make transmission/reception efficient by repetition, it is necessaryto configure an optimal number of repetitions by the MTCUE or the basestation device, and to manage the number of repetitions of the MTCUE orthe base station device.

The present invention provides a terminal device, a monitoring method,and an integrated circuit that allow a terminal device and a basestation device to efficiently perform transmission/reception byrepetition.

Means for Solving the Problems

(1) A terminal device according to an embodiment of the presentinvention is a terminal device configured with the number of repetitivetransmissions and/or repetitive receptions. The terminal device includesa physical layer control part configured to monitor a radio link on thebasis of a specific threshold value defined as a level of a downlinkradio link. The threshold value is defined by taking into account thenumber of repetitive transmissions and/or repetitive receptions.

(2) Further, a control method according to the embodiment of the presentinvention is a monitoring method applied to a terminal device configuredwith the number of repetitive transmissions and/or repetitivereceptions. The method includes at least the step of monitoring a radiolink on the basis of a specific threshold value defined as a level of adownlink radio link. The threshold value is defined by taking intoaccount the number of repetitive transmissions and/or repetitivereceptions.

(3) Further, an integrated circuit according to the embodiment of thepresent invention is an integrated circuit mounted in a terminal deviceconfigured with the number of repetitive transmissions and/or repetitivereceptions. The integrated circuit causes the terminal device to exertthe function of monitoring a radio link on the basis of a specificthreshold value defined as a level of a downlink radio link. Thethreshold value is defined by taking into account the number ofrepetitive transmissions and/or repetitive receptions.

Effects of the Invention

As described above, according to the embodiments of the presentinvention, there can be provided a terminal device, a monitoring method,and an integrated circuit that allow a terminal device to efficientlyperform repeated transmission/reception control, and allow a basestation device to efficiently perform data scheduling with respect to aterminal device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a configuration of aterminal device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a configuration of a basestation device according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a sequence chart forconfiguring the number of transmission repetitions and the number ofreception repetitions at the time of an initial random access, accordingto the embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a sequence chart forconfiguring the number of repetitions in a random access procedure,according to a first embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of a sequence chart forconfiguring the number of repetitions in a random access procedure,according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of a physical channelconfiguration in an LTE.

FIG. 7 is a diagram illustrating an example of a downlink channelconfiguration in the LTE.

FIG. 8 is a diagram illustrating an example of an uplink channelconfiguration in the LTE.

FIG. 9 is a diagram illustrating a configuration example of acommunication protocol relating to control information of the basestation device and the terminal device.

FIG. 10 is a diagram illustrating a configuration example of acommunication protocol relating to user information of the base stationdevice and the terminal device.

FIG. 11 is a diagram illustrating a contention based random accessprocedure.

FIG. 12 is a diagram illustrating a non-contention based random accessprocedure.

MODE FOR CARRYING OUT THE INVENTION

An OFDM scheme is employed for downlink in the LTE. Furthermore, asingle carrier communication scheme based on a DFT-spread OFDM scheme isemployed for uplink in the LTE.

FIG. 6 is a diagram illustrating an LTE physical channel configuration.A downlink physical channel is constituted of a physical downlink sharedchannel (PDSCH), a physical downlink control channel (PDCCH), and aphysical broadcast channel (PBCH). Additionally, physical signals suchas a downlink synchronization signal and a downlink reference signal areprovided (NPL 1).

An uplink physical channel is constituted of a physical random accesschannel (PRACH), a physical uplink shared channel (PUSCH), and aphysical uplink control channel (PUCCH). Additionally, physical signalssuch as an uplink reference signal are provided. The uplink referencesignal includes a demodulation reference signal (DRS) and a soundingreference signal (SRS). Furthermore, the sounding reference signalincludes a periodic SRS and an aperiodic SRS. Hereinafter, unlessotherwise indicated, the sounding reference signal refers to theperiodic SRS (NPL 1).

FIG. 7 is a diagram illustrating an LTE downlink channel configuration.The downlink channel illustrated in FIG. 7 is constituted of a logicalchannel, a transport channel, and a physical channel. The logicalchannel defines types of transfer services of data to betransmitted/received in a medium access control (MAC) layer. Thetransport channel defines what characteristics data to be transmittedover a radio interface has, and how the data is transmitted. Thephysical channel is configured to carry data transported to the physicallayer by the transport channel.

The downlink logical channel includes a broadcast control channel(BCCH), a paging control channel (PCCH), a common control channel(CCCH), a dedicated control channel (DCCH), and a dedicated trafficchannel (DTCH).

The downlink transport channel includes a broadcast channel (BCH), apaging channel (PCH), and a downlink shared channel (DL-SCH).

The downlink physical channel includes the physical broadcast channel(PBCH), the physical downlink control channel (PDCCH), and the physicaldownlink shared channel (PDSCH). These channels are transmitted/receivedbetween the base station device and the terminal device.

Next, the logical channel will be described. The broadcast controlchannel BCCH is a downlink channel used to broadcast system controlinformation. The paging control channel PCHH is a downlink channel usedto transmit paging information, and is used when the network does notknow the cell position of a terminal device. The common control channelCCCH is a channel used to transmit control information between terminaldevices and a network, and is used by terminal devices that do not havea radio resource control (RRC) connection to the network.

The dedicated control channel DCCH is a point-to-point bidirectionalchannel, and is utilized to transmit individual pieces of controlinformation between terminal devices and a network. The dedicatedcontrol channel DCCH is used by terminal devices that have an RRCconnection. The dedicated traffic channel DTCH is a point-to-pointbidirectional channel dedicated to one terminal device, and is utilizedto transfer user information (unicast data).

Next, the transport channel will be described. The broadcast channel BCHis broadcast to the entire cell in accordance with a transmission formatthat is fixedly defined beforehand. The downlink shared channel DL-SCHsupports hybrid automatic repeat request (HARQ), dynamic adaptationradio link control, and discontinuous reception (DRX), and needs to bebroadcast to the entire cell.

The paging channel PCH supports the DRX, and needs to be broadcast tothe entire cell. Additionally, the paging channel PCH is mapped to aphysical resource, i.e., the physical downlink shared channel PDSCHwhich is used dynamically with respect to the traffic channels and othercontrol channels.

Next, the physical channel will be described. The physical broadcastchannel PBCH has the broadcast channel BCH mapped thereto at 40 msintervals. The physical downlink control channel PDCCH is a channel usedto notify a terminal device of a radio resource assignment of thedownlink shared channel PDSCH (downlink assignment), hybrid automaticrepeat request (HARQ) information on downlink data, and uplinktransmission permission (uplink grant) that corresponds to a radioresource assignment of the physical uplink shared channel PUSCH. Thephysical downlink shared channel PDSCH is a channel used to transmitdownlink data or paging information.

Note that the physical downlink control channel PDCCH occupies the firstto third OFDM symbols of a resource block in one subframe, and thedownlink shared channel PDSCH occupies the remaining OFDM symbols. Onesubframe is constituted of two resource blocks, and one frame isconstituted of 10 subframes. One resource block is constituted of 12subcarriers and 7 OFDM symbols.

When the base station device has notified the terminal device of a radioresource assignment of a physical downlink shared channel PDSCH to theterminal device on the physical downlink control channel PDCCH, a regionof the physical downlink shared channel PDSCH assigned to the terminaldevice is a physical downlink shared channel PDSCH within the samesubframe of the physical downlink control channel PDCCH on which theterminal device has been notified of the downlink assignment.

Next, channel mapping will be described. As illustrated in FIG. 7, inthe downlink, mapping between the transport channel and the physicalchannel takes place as follows. The broadcast channel BCH is mapped tothe physical broadcast channel PBCH. The paging channel PCH and thedownlink shared channel DL-SCH are mapped to the physical downlinkshared channel PDSCH. The physical downlink control channel PDCCH isused as an independent physical channel.

Additionally, in the downlink, mapping between the logical channel andthe transport channel takes place as follows. The paging control channelPCCH is mapped to the paging channel PCH. The broadcast control channelBCCH is mapped to the broadcast channel BCH and the downlink sharedchannel DL-SCH. The common control channel CCCH, the dedicated controlchannel DCCH, and the dedicated traffic channel DTCH are mapped to thedownlink shared channel DL-SCH.

FIG. 8 is a diagram illustrating an LTE uplink channel configuration.The uplink channel illustrated in FIG. 8 is constituted of a logicalchannel, a transport channel, and a physical channel. The channels aredefined in the same manner as the downlink channels.

The uplink logical channel includes a common control channel (CCCH), adedicated control channel (DCCH), and a dedicated traffic channel(DTCH).

The uplink transport channel includes an uplink shared channel (UL-SCH)and a random access channel (RACH).

The uplink physical channel includes a physical uplink control channel(PUCCH), a physical uplink shared channel (PUSCH), and a physical randomaccess channel (PRACH). These channels are transmitted/received betweenthe base station device and the terminal device.

Next, the logical channel will be described. The common control channelCCCH is a channel used to transmit control information between terminaldevices and a network, and is used by a terminal device or base stationdevice when the terminal device has not moved to a state of having aradio resource control (RRC) connection with the network (RRC connectedstate, RRC_CONNECTED).

The dedicated control channel DCCH is a point-to-point bidirectionalchannel, and is utilized to transmit individual pieces of controlinformation between terminal devices and a network. The dedicatedcontrol channel DCCH is used by terminal devices that have an RRCconnection. The dedicated traffic channel DTCH is a point-to-pointbidirectional channel dedicated to one terminal device, and is utilizedto transfer user information (unicast data).

Next, the transport channel will be described. The uplink shared channelUL-SCH supports hybrid automatic repeat request (HARQ), dynamicadaptation radio link control, and discontinuous transmission (DTX). Onthe random access channel RACH, limited control information istransmitted.

Next, the physical channel will be described. The physical uplinkcontrol channel PUCCH is a channel used to notify the base stationdevice of response information (acknowledge (ACK)/negative acknowledge(NACK)) on downlink data, downlink radio quality information, and anuplink data transmission request (scheduling request: SR). The physicaluplink shared channel PUSCH is a channel used to transmit uplink data.The physical random access channel PRACH is used primarily for randomaccess preamble transmission, in order to acquire information abouttransmission timing from the terminal device to the base station device.The random access preamble transmission takes place during the randomaccess procedure.

Next, channel mapping will be described. As illustrated in FIG. 8, inthe uplink, mapping between the transport channel and the physicalchannel takes place as follows. The uplink shared channel UL-SCH ismapped to the physical uplink shared channel PUSCH. The random accesschannel RACH is mapped to the physical random access channel PRACH. Thephysical uplink control channel PUCCH is used as an independent physicalchannel.

Additionally, in the uplink, mapping between the logical channel and thetransport channel takes place as follows. The common control channelCCCH, the dedicated control channel DCCH, and the dedicated trafficchannel DTCH are mapped to the uplink shared channel UL-SCH.

FIG. 9 illustrates a protocol stack for handling control data of an LTEterminal device and base station device. FIG. 10 illustrates a protocolstack for handling user data of the LTE terminal device and base stationdevice. FIG. 9 and FIG. 10 will be described below.

The physical layer (PHY layer) provides a transfer service to a higherlayer. The PHY layer is connected to an upper medium access controllayer (MAC layer) via the transport channel. Data moves between the MAClayer and the PHY layer via the transport channel. Between the PHYlayers of the terminal device and base station device, data istransmitted/received via the physical channel.

The MAC layer causes various logical channels to be mapped to varioustransport channels. The MAC layer is connected to an upper radio linkcontrol layer (RLC layer) via the logical channels. The logical channelsare broadly classified into a control channel for transferring controlinformation and a traffic channel for transferring user data, inaccordance with the type of information transferred thereon. The MAClayer is capable of controlling the PHY layer for discontinuousreception/transmission (DRX/DTX), providing notification of informationon transmit power, carrying out HARQ control, and the like.

The MAC layer is also capable of providing notification of the amount ofdata in a transmission buffer that corresponds to each of the logicalchannels (buffer status report: BSR), and carrying out a radio resourcerequest for transmission of uplink data (scheduling request). The MAClayer executes a random access procedure for initial access, ascheduling request, or the like.

The MAC layer is also capable of, when the carrier aggregation isenabled, controlling the PHY layer for activation/deactivation of a celland controlling the PHY layer for management of the uplink transmissiontiming.

The RLC layer performs segmentation and concatenation of data receivedfrom a higher layer, and adjusts the data size to one such that a lowerlayer can transmit the data appropriately. The RLC layer is also capableof ensuring quality of service (QoS) required of each piece of data.That is, the RLC layer is capable of data re-transmission control andthe like.

The packet data convergence protocol layer (PDCP layer) has a headercompression function of compressing unneeded control information inorder to achieve efficient transfer of IP packets, namely user data, inradio sections. The PDCP layer is also capable of encoding data.

In the radio resource control layer (RRC layer), only controlinformation is defined. The RRC layer configures/re-configures radiobearers (RBs), and controls the logical channels, transport channels,and physical channels. The RBs are classified into a signaling radiobearer (SRB) and a data radio bearer (DRB). The SRB is utilized as atransmission path for a RRC message that is control information. The DRBis utilized as a transmission path for user information. Each of the RBsis configured between the respective RRC layers of the base stationdevice and the terminal device.

Note that the PHY layer corresponds to the physical layer that is Layer1 of the hierarchical structure of the widely-known open systemsinterconnection (OSI) model; the MAC layer, the RLC layer, and the PDCPlayer correspond to the data link layer that is Layer 2 of the OSImodel; and the RRC layer corresponds to the network layer that is Layer3 of the OSI model.

Next, the random access procedure will be described. The random accessprocedure includes two access procedures: a contention based randomaccess procedure, and a non-contention based random access procedure(NPL 1).

FIG. 11 is a diagram illustrating the contention based random accessprocedure. The contention based random access procedure involves randomaccess that may cause contention (collision) between terminal devices.The contention based random access procedure is used: at the time ofinitial access with no connection (communication) established with thebase station device; for making a scheduling request when uplink datatransmission has occurred in the terminal device with a connectionestablished with the base station device but with uplink synchronizationlost; or the like.

FIG. 12 is a diagram illustrating a non-contention based random accessprocedure. The non-contention based random access procedure involvesrandom access that causes no contention between terminal devices, and isused to rapidly achieve uplink synchronization between the terminaldevice and the base station device when the terminal device and the basestation device are connected but uplink synchronization is lost. In thenon-contention based random access procedure, the terminal device isinstructed by the base station device to initiate random access, forexample, during handover, when the transmission timing of the terminaldevice is invalid, or other exceptional cases (NPL 1). Thenon-contention based random access procedure is instructed by the radioresource control (RRC, Layer 3) layer message and control data on thedownlink control channel PDCCH.

The contention based random access procedure will be briefly describedwith reference to FIG. 11. First, a terminal device 1-1 transmits arandom access preamble to a base station device 3 (message 1: (1), stepS111). Having received the random access preamble, the base stationdevice 3 transmits a response to the random access preamble (a randomaccess response message) to the terminal device 1-1 (message 2: (2),step S112). On the basis of scheduling information included in therandom access response, the terminal device 1-1 transmits a higher layer(Layer 2/Layer 3) message (message 3: (3), step S113). The base stationdevice 3 transmits a contention resolution message to the terminaldevice 1-1 from which the base station device 3 has successfullyreceived the higher layer message of (3) (message 4: (4), step S114).Note that the contention based random access is also called randompreamble transmission.

The non-contention based random access procedure will be brieflydescribed with reference to FIG. 12. First, the base station device 3notifies the terminal device 1-1 of a preamble number (or a sequencenumber), and a random access channel number to be used (message 0: (1′),step S121). The terminal device 1-1 transmits the random access preamblecorresponding to the specified preamble number to the specified randomaccess channel RACH (message 1: (2′), step S122). Having received therandom access preamble, the base station device 3 transmits a responseto the random access preamble (a random access response message) to theterminal device 1-1 (message 2: (3′), step S123). However, when thepreamble number notified in step S121 is zero, the contention basedrandom access procedure is performed. Note that the non-contention basedrandom access is also called dedicated preamble transmission.

The connection procedure to the base station device 3 by the terminaldevice 1-1 will be described with reference to FIG. 11. First, theterminal device 1-1 acquires system information on the base stationdevice 3 via the physical broadcast channel PBCH or the like, executes arandom access procedure in accordance with random access-relatedinformation included in the system information, and connects to the basestation device 3. From the random access-related information in thesystem information and the like, the terminal device 1-1 generates arandom access preamble. The terminal device 1-1 then transmits therandom access preamble on the random access channel RACH (message 1:(1)).

Upon detecting the random access preamble from the terminal device 1-1,the base station device 3 calculates, from the random access preamble,the amount of deviation of transmission timing between the terminaldevice 1-1 and the base station device 3, performs scheduling fortransmitting a Layer 2 (L2)/Layer 3 (L3) message (specifying an uplinkradio resource position (position of the uplink shared channel PUSCH), atransmission format (message size), and the like), assigns a cell-radionetwork temporary identity (temporary C-RNTI: terminal deviceidentification information), maps, on the physical downlink controlchannel PDCCH, a random access-radio network temporary identity(RA-RNTI, random access response identification information) indicatinga response (random access response) addressed to the terminal device 1-1that has transmitted the random access preamble of the random accesschannel RACH, and transmits on the physical downlink shared channelPDSCH a random access response message that includes transmission timinginformation, scheduling information, the temporary C-RNTI, and thereceived random access preamble information (message 2: (2)).

Upon detecting that the presence of the RA-RNTI on the physical downlinkcontrol channel PDCCH, the terminal device 1-1 checks the content of therandom access response message mapped on the physical downlink sharedchannel PDSCH, and when the transmitted random access preambleinformation has been found therein, adjusts the uplink transmissiontiming on the basis of the transmission timing information, andtransmits an L2/L3 message that includes information identifying theterminal device 1-1, such as a C-RNTI (or temporary C-RNTI), aninternational mobile subscriber identity (IMSI), or the like, using thescheduled radio resource and transmission format (message 3: (3)).

When the transmission timing has been adjusted, the terminal device 1-1starts a transmission timing timer. While the transmission timer is inoperation (running), the transmission timing is valid, and when thetransmission timing timer expires or stops, the transmission timing isinvalid. When the transmission timing is valid, the terminal device 1-1is allowed to transmit data to the base station device 3, whereas whenthe transmission timing is invalid, the terminal device 1-1 is allowedto transmit only a random access preamble. Furthermore, a period duringwhich the transmission timing is valid is called an uplink synchronousstate, and a period during which the transmission timing is invalid iscalled an uplink asynchronous state.

Upon receiving the L2/L3 message from the terminal device 1-1, the basestation device 3, using the C-RNTI (or temporary C-RNTI) or the IMSIincluded in the received L2/L3 message, transmits to the terminal device1-1 a contention resolution message for determining whether contention(collision) is occurring among the terminal devices 1-1 to 1-3 (message4: (4)).

Note that upon having not detected a random access response message thatincludes a preamble number corresponding to the transmitted randomaccess preamble within a specified period of time, upon having failed totransmit the message 3, or upon having not detected identificationinformation on the terminal device 1-1 in the contention resolutionmessage within a specified period of time, the terminal device 1-1starts the process over from transmission of a random access preamble(message 1: (1)).

Then, when the number of random access preamble transmissions hasexceeded the maximum number of random access preamble transmissionsindicated by the system information, the terminal device 1-1 determinesthat a problem has occurred with random access, and notifies the RRClayer of the existence of the problem with random access. In accordancewith an instruction from the RRC layer or the MAC layer, the terminaldevice 1-1 terminates the random access procedure. Note that uponsuccessful completion of the random access procedure, control data forconnection is further exchanged between the base station device 3 andthe terminal device 1-1. At this time, the base station device 3notifies the terminal device 1-1 of an individually-assigned uplinkreference signal, or assignment information on the physical uplinkcontrol channel PUCCH.

To update an uplink transmission timing applied after the completion ofthe random access procedure, the base station device 3 measures anuplink reference signal (a measurement reference signal or demodulationreference signal) transmitted from the terminal device 1-1, calculatesthe uplink transmission timing, and notifies the terminal device 1-1 ofa transmission timing message that includes the calculated transmissiontiming information.

Upon updating the transmission timing indicated in the transmissiontiming message notified by the base station device 3, the terminaldevice 1-1 restarts the transmission timing timer. Note that the basestation device 3 also retains the same transmission timing timer as thatof the terminal device 1-1, and starts or restarts the transmissiontiming timer upon transmitting transmission timing information. Thisconfiguration allows the base station device 3 and the terminal device1-1 to manage an uplink synchronous state. Note that when thetransmission timing timer has expired, or when the transmission timingtimer is not in operation, the transmission timing is invalid.

In the 3GPP, the LTE-Advanced, which is a further evolution of LTE, isalso under discussion. In the LTE-Advanced, it is envisaged to use bandshaving a maximum bandwidth of up to 100 MHz for each of uplink anddownlink, to perform communication at maximum transfer rates of 1 Gbpsor more for downlink, and 500 Mbps or more for uplink.

In the LTE-Advanced, it is contemplated to achieve a band of a maximumof 100 MHz by binding together multiple LTE bands of 20 MHz or narrower,so as to be able to accommodate LTE terminal devices as well. Note thatfor the LTE-Advanced, a single LTE band of 20 MHz or narrower is calleda component carrier (CC) (NPL 1).

In addition, a single downlink component carrier and a single uplinkcomponent carrier are combined to constitute a single cell. Note that asingle cell can also be constituted of a single downlink componentcarrier only. Communications between the base station device and theterminal device via aggregated multiple cells are termed carrieraggregation.

In carrier aggregation, a single base station device assigns multiplecells that match the communication capabilities and communicationconditions of the terminal device, and carrying out communication withthe terminal device via the assigned multiple cells. Note that one ofthe multiple cells assigned to the terminal device is defined as a firstcell (primary cell (PCell)), and the other cells are defined as secondcells (secondary cells (SCells)). The primary cell is assigned withfunctions, such as assignment of the physical uplink control channelPUCCH, that are not performed in the secondary cells.

In addition, for the LTE-Advanced, issues relating to lowering the costof terminal devices that support machine type communication (MTC) ormachine type communication (M2M) are under examination (NPL 2).Hereinbelow, an MTC/M2M terminal device or an MTC/M2M communicationdevices will also be referred to as machine type communication userequipment (MTCUE).

In order to realize low-cost MTCUE while maintaining backwardcompatibility with systems compliant with the LTE standard andLTE-Advanced standard, cost reduction methods have been proposed, suchas narrowing the transmission/reception bandwidth, reducing the numberof antenna ports/number of RF chains, lowering thetransmission/reception data transfer rate, adopting the half-duplexfrequency division duplex scheme, reducing the transmit/receive power,and extending the discontinuous reception interval. It has also beenproposed that reducing the maximum bandwidth of MTCUEtransmission/reception RF circuit or transmission/reception basebandcircuit would be effective as a method for realizing low-cost MTCUE.

Of issues under study in relation to MTC, cost reductions are not theonly issue being studied, and coverage enhancement (CE) for enhancingthe transmission/reception range of MTCUE is also currently a subject ofstudy. For example, whereas costs can be reduced by lowering the maximumtransmit power of terminal devices, or simplifying the reception circuit(such as by receiving with a single antenna instead of receiving withmultiple antennas), uplink coverage reduction due to reduced maximumtransmit power, and downlink coverage reduction due to reduced gainduring reception due to simplification of the reception circuit, areconceivable, and therefore issues under study in relation to coverageenhancement include enhancing these to the normal coverage range. Inorder to reduce the transmit/receive power and enhance coverage, it isconceivable for the base station device to repeatedly transmit downlinkdata or a downlink signal to the MTCUE, and for the MTCUE to repeatedlytransmit uplink data or an uplink signal to the base station device.Such repeated transmission includes transmission of the same data with adifferent redundancy version in the HARQ process, transmission with thesame redundancy version, repeated transmission of the control channel inmultiple subframes, and the like. Such novel functions (reduction in themaximum bandwidth, repeated transmission, and the like) merely specifythe type of terminal device, and application thereof is not limited toMTC.

For example, the base station device repeatedly transmits, to the MTCUE,the physical broadcast channel PBCH multiple times within 40 ms.Furthermore, the base station device repeatedly transmits, multipletimes to the MTCUE, the physical downlink shared channel PDSCH, thephysical downlink control channel PDCCH, the enhanced physical controlchannel EPDCCH, and the like. The MTCUE repeatedly transmits, multipletimes to MTCUE, the physical uplink shared channel PUSCH, the physicaluplink control channel PUCCH, and the like. In the random accessprocedure, the MTCUE repeatedly transmits the same random accesspreamble, using radio resources of multiple random access channelsPRACHs. Having received the random access preamble, the base stationdevice repeatedly transmits a random access response message. Themessage 3 and a contention resolution message are repeatedly transmittedas well.

Such a configuration in which repeatedly-transmitted data is repeatedlyreceived and the received pieces of data are composited allows coverageto be enhanced. Furthermore, the amount of coverage enhancement (CE)required differs depending on the arrangement and distance between theterminal device and the base station device, which requires that thenumber of repetitions (or a parameter corresponding to the number ofrepetitions (also termed the repetition level or cell enhancementlevel)) be appropriately configured for each terminal device (or eachphysical channel used by terminal devices).

For this reason, a configuration is under study in which the basestation device notifies MTCUE within a cell of the number of repetitionsusing the broadcast channel BCH, or individually notifies MTCUE of thenumber of repetitions (NPL 3).

For example, notification of the number of transmission repetitions ofrandom access preamble or the number of reception repetitions of randomaccess response message is made using the broadcast channel BCH. Anotherconfiguration is under study in which multiple different numbers oftransmission repetitions of random access preamble are defined, and theMTCUE is allowed to select one from among the multiple different numbersof transmission repetitions.

Repetition control for physical downlink control channel PDCCHreception, enhanced physical control channel EPDCCH reception, physicaluplink control channel PUCCH transmission, and physical random accesschannel PRACH (or random access preamble) transmission is calledphysical repetition (PHY repetition), and repetition control forphysical downlink shared channel PDSCH reception and physical uplinkshared channel PUSCH transmission is called bundling.

When the bundling is configured, the bundle size provides the number ofsubframes of a single bundle. The bundling operation relies on a HARQentity for invoking the same HARQ process for each transmission that ispart of the same bundle. Within a single bundle, HARQ retransmissionsare non-adaptive and triggered without waiting for feedback fromprevious transmissions according to the bundle size. HARQ feedback of asingle bundle is received (PUSCH HARQ-ACK) or transmitted (PDSCHHARQ-ACK) by a terminal device, for only the last subframe of thebundle. The bundling process takes place in the MAC layer.

Transmission of system information to be broadcast is performedperiodically at the RRC layer level. In transmission of each systeminformation, HARQ retransmission takes place in the MAC layer.Repetition control for physical downlink control channel PDCCHreception, enhanced physical control channel EPDCCH reception, physicaluplink control channel PUCCH transmission, and physical random accesschannel PRACH (or random access preamble) transmission takes place inthe PHY layer.

Furthermore, the base station device 3 may configure multiple differentnumbers of repetitions and configure respective repetition levels orbundling sizes. For example, with three repetition levels configured,when the repetition level is 1, the number of repetitions is set to 10;when the repetition level is 2, the number of repetitions is set to 20;and when the repetition level is 3, the number of repetitions is set to30. At this time, different numbers of repetitions may be set forrespective channels. The base station device 3 may be configured toindividually notify the terminal device 1-1 of the repetition levels orbundling sizes.

A dedicated downlink control channel for the MTCUE (MPDCCH) may bedefined. In this case, the MPDCCH may fulfill some or all of the rolesof the above-described PDCCH and EPDCCH for the MTCUE.

In light of the foregoing, preferred embodiments of the presentinvention will be described in detail below, with reference to theappended drawings. Note that in the descriptions of the embodiments ofthe present invention, when it is determined that detailed descriptionsof widely-known functions and configurations related to the embodimentsof the present invention make the gist of the embodiments of the presentinvention unclear, the detailed descriptions will be omitted.

First Embodiment

A first embodiment of the present invention will be described below.

FIG. 1 is a diagram illustrating a configuration of a terminal deviceaccording to the embodiment of the present invention. Terminal devices1-1 to 1-3 are each constituted of a data generation part 101, atransmission data storage part 103, a transmission processing part 105,a radio part 107, a reception processing part 109, a MAC informationextraction part 111, a data processing part 113, a PHY control part(physical layer control part) 115, a MAC control part (medium accesscontrol part) 117, and an RRC control part (radio resource control part)119. In FIG. 1, “part” refers to an element for implementing thefunction and procedure of the terminal device 1, and may also bereferred to as “section,” “circuit,” “constituent device,” “device,” or“unit.”

User data from the higher layer and control data from the RRC controlpart 119 are input to the data generation part 101. The data generationpart 101 has functions of the PDCP layer and the RLC layer. The datageneration part 101 performs processes such as user data IP packetheader compression, data encryption, and segmentation and concatenationof data, and adjusts the data size. The data generation part 101 outputsthe processed data to the transmission data storage part 103.

The transmission data storage part 103 accumulates the data input fromthe data generation part 101, and in accordance with an instruction fromthe MAC control part 117, outputs the specified data to the transmissionprocess part 105 by the specified data volume. The transmission datastorage part 103 also outputs information regarding the volume ofaccumulated data to the MAC control part 117.

The transmission processing part 105 codes the data input from thetransmission data storage part 103, and performs a puncture process onthe coded data. The transmission processing part 105 modulates and codesthe punctured data. The transmission processing part 105 then performsdiscrete Fourier transform (DFT)-inverse fast Fourier transform (IFFT)on the modulated and coded data, and thereafter inserts a cyclic prefix(CP), maps the CP-inserted data on the physical uplink shared channel(PUSCH) of each component carrier (cell) in the uplink, and outputs thedata to the radio part 107.

Upon having received a response instruction to received data from thePHY control part 115, the transmission processing part 105 generates anACK or a NACK signal, maps the generated signal on the physical uplinkcontrol channel (PUCCH), and outputs the signal to the radio part 107.Upon having received a transmission instruction for random accesspreamble from the PHY control part 115, the transmission processing part105 generates a random access preamble, maps the generated signal on thephysical random access channel PRACH, and outputs the signal to theradio part 107.

The radio part 107 upconverts the data input from the transmissionprocessing part 105 to a radio frequency of transmission positioninformation (transmission cell information) instructed by the PHYcontrol part 115, adjusts the transmit power, and transmits the datafrom a transmit antenna. The radio part 107 downcoverts radio signalsreceived via a receive antenna, and outputs the signals to the receptionprocessing part 109. The radio part 107 configures the transmissiontiming information received from the PHY control part 115 as the uplinktransmission timing.

The reception processing part 109 performs a fast Fourier transform(FFT) process, decoding, a demodulation process, and the like on thesignals input from the radio part 107. The reception processing part 109demodulates the physical downlink control channel PDCCH or the enhancedphysical downlink control channel EPDCCH. Upon detection of downlinkassignment information for the own terminal device, the receptionprocessing part 109 demodulates the physical downlink shared channelPDSCH on the basis of the downlink assignment information, and outputs,to the MAC control part 117, the notice of receipt of the downlinkassignment information. Furthermore, during the aforementioned process,the reception processing part 109 may perform processing in such a wayas to composite multiple input signals on the basis of the number ofrepetitions instructed by the PHY control part 115.

The reception processing part 109 decodes the demodulated physicaldownlink shared channel PDSCH data. Upon succeeding in decoding thedata, the reception processing part 109 outputs the data to the MACinformation extraction part 111. The reception processing part 109demodulates the physical downlink control channel PDCCH or the enhancedphysical downlink control channel EPDCCH. Upon detection of uplinktransmission permission information (an uplink grant) or responseinformation on uplink transmission data (ACK/NACK), the receptionprocessing part 109 outputs the acquired response information to the MACcontrol part 117. Note that the uplink transmission permissioninformation includes data modulation and coding schemes, data sizeinformation, HARQ information, transmission position information, andthe like. Furthermore, the reception processing part 109 notifies theMAC control part 117 of the success or failure in decoding the inputdata.

Furthermore, the reception processing part 109 may measure downlinkreference signal received power (RSRP), the downlink reference signalbeing known sequence signal, and report the measurement result to theRRC control part 119 via the PHY control part 115. When doing so, thereception processing part 109 may change the measurement period inaccordance with the number of reception repetitions (repetition level,bundling size) configured by the PHY control part 115. The informationon the measurement period configured in accordance with the number ofrepetitions may be formed of predefined combinations or may be notifiedor broadcast by means of an RRC message from the base station device 3.

The MAC information extraction part 111 extracts the medium accesscontrol layer (MAC layer) control data from data input from thereception processing part 109, and outputs the extracted MAC controlinformation to the MAC control part 117. The MAC information extractionpart 111 outputs the remaining data to the data processing part 113. Thedata processing part 113 has functions of the PDCP layer and the RLClayer, and performs processing, such as an expansion (decompression)function for compressed IP headers, a decoding function for coded data,and segmentation and concatenation of data, to restore the data to theoriginal form thereof. The data processing part 113 divides the datainto a RRC message and user data, and then outputs the RRC message tothe RRC control part 119 and the user data to the higher layer.

In accordance with instructions from the MAC control part 117, the PHYcontrol part 115 controls the transmission processing part 105, theradio part 107, and the reception processing part 109. From themodulation and coding schemes, transmit power information, andtransmission position information (transmission cell information)notified by the MAC control part 117, the PHY control part 115 notifiesthe transmission processing part 105 of the modulation and codingschemes and the transmission position, and notifies the radio part 107of the transmission cell frequency information and transmit powerinformation. Furthermore, in accordance with instructions from the MACcontrol part 117, the PHY control part 115 performs ON/OFF control onpower (power supply) of the transmission processing part 105, the radiopart 107, and the reception processing part 109. The ON/OFF controlrefers to power-saving control, including bringing the power supply downto standby power.

A control signal specifying the number of uplink and/or downlinkrepetitions is input to the PHY control part 115 from any one of thereception processing part 109, the MAC control part 117, and the RRCcontrol part 119.

The MAC control part 117 has functions of the MAC layer, and controlsthe MAC layer on the basis of information acquired from the RRC controlpart 119, the lower layer, and the like. On the basis of the datatransmission control configuration specified by the RRC control part119, data volume information acquired from the transmission data storagepart 103, and uplink transmission permission information acquired fromthe reception processing part 109, the MAC control part 117 determines adata transmission destination and a data transmission priority order,and notifies the transmission data storage part 103 of informationrelating to data to be transmitted. The MAC control part 117 alsooutputs the modulation and coding schemes and transmission positioninformation (transmission cell information) to the PHY control part 115.

The MAC control part 117 acquires transmission timing timer informationfrom the RRC control part 119. Using the transmission timing timer, theMAC control part 117 manages the valid/invalid status of the uplinktransmission timing. The MAC control part 117 outputs, to the PHYcontrol part 115, transmission timing information which is included in atransmission timing message in MAC control information input from theMAC information extraction part 111. Upon having configured atransmission timing, the MAC control part 117 starts or restarts thetransmission timing timer.

The MAC control part 117 creates a buffer status report (BSR), which isinformation about the amount of data accumulated in the transmissiondata storage part 103, and outputs the report to the transmission datastorage part 103. The MAC control part 117 also creates a power headroomreport (PHR), which is transmit power information, and outputs thereport to the transmission data storage part 103.

When configuration information on the number of repetitions (firstinformation) is included in a random access response message input fromthe MAC information extraction part 111, the MAC control part 117 maynotify the PHY control part 115, on the basis of the first information,of a configuration for the number of transmission repetitions of themessage 3; and even when information on the number of repetitions(second information) notified by the RRC control part 119 is present,the MAC control part 117 may notify the PHY control part 115, on thebasis of the first information, of a configuration for the number ofreception repetitions of the contention resolution message. Furthermore,the configuration information on the number of repetitions may benotified to the RRC control part 119.

A control signal specifying the number of uplink and/or downlinkrepetitions may be input to the MAC control part 117 from the MACinformation extraction part 111 and/or the RRC control part 119.Furthermore, the MAC control part 117 may output the information on thenumber of repetitions to the PHY control part 115.

The RRC control part 119 performs various configurations forcommunications with the base station device 3, such as processes ofconnecting with/disconnecting from the base station device 3, and datatransmission control configuration for control data and user data. TheRRC control part 119 exchanges information with the higher layer inassociation with the various configurations, and control the lower layerin association with the various configurations.

The RRC control part 119 creates an RRC message, and outputs the createdRRC message to the data generation part 101. The RRC control part 119analyzes the RRC message input from the data processing part 113. TheRRC control part 119 creates a message indicating the transmissioncapability of the own terminal device, and outputs the message to thedata generation part 101. Furthermore, the RRC control part 119 alsooutputs information necessary for the MAC layer to the MAC control part117, and outputs information necessary for the physical layer to the PHYcontrol part 115.

Upon having acquired transmission timing timer information, the RRCcontrol part 119 outputs the transmission timing timer information tothe MAC control part 117. Upon having been notified of the release ofthe physical uplink control channel PUCCH or uplink sounding referencesignal from the MAC control part 117, the RRC control part 119 releasesthe assigned physical uplink control channel PUCCH and uplink soundingreference signal, and instructs the PHY control part 115 to release thephysical uplink control channel PUCCH and the uplink sounding referencesignal.

Information specifying the number of uplink and/or downlink receptionsmay be input to the RRC control part 119 from the data processing part113. Furthermore, the RRC control part 119 may output the information onthe number of repetitions to the MAC control part 117 and/or the PHYcontrol part 115.

On the basis of information on the received power (RSRP) reported by thereception processing part 109 and information notified or broadcast bymeans of an RRC message from the base station device 3, the RRC controlpart 119 may derive the number of repetitions to be configured for theown terminal device and/or to be notified (or reported, or requested) tothe base station device 3. In this case, the RRC control part 119 mayoutput the information on the number of repetitions to the MAC controlpart 117 and/or the PHY control part 115. The information on the numberof repetitions may be information that is configured for each physicalchannel, or information that is configured for only some of the physicalchannels.

On the basis of the information on the number of receptions input fromthe RRC control part 119, the MAC control part 117 and/or the PHYcontrol part 115 may configure the number of transmission repetitionsand/or the number of reception repetitions for the own terminal device.The number of repetitions may be configured on a channel-by-channelbasis.

Note that the transmission processing part 105, the radio part 107, thereception processing part 109, and the PHY control part 115 performphysical layer operations, the transmission data storage part 103, theMAC information extraction part 111, and the MAC control part 117perform MAC layer operations, the data generation part 101 and the dataprocessing part 113 perform RLC layer and PDCP layer operations, and theRRC control part 119 performs RRC layer operations. One or multiplecontrol parts may be constituted of some or all of the PHY control part115, the MAC control part 117, and the RRC control part 119.

In FIG. 1, other constituent elements of the terminal device 1, and data(control information) transmission paths between constituent elementshave been omitted, but it is obvious that the terminal device 1includes, as constituent elements thereof, multiple blocks having otherfunctions necessary for operating as the terminal device 1. For example,a non access stratum (NAS) layer part and an application layer part arepresent above the RRC control part 119.

FIG. 2 is a diagram illustrating a configuration of the base stationdevice according to the embodiment of the present invention. The basestation device 3 is constituted of a data generation part 201, atransmission data storage part 203, a transmission processing part 205,a radio part 207, a reception processing part 209, a MAC informationextraction part 211, a data processing part 213, a PHY control part 215,a MAC control part 217, and an RRC control part 219. In FIG. 2, “part”refers to an element for implementing the function and procedure of thebase station device 3, and may also be referred to as “section,”“circuit,” “constituent device,” “device,” or “unit.”

The data generation part 201 has functions of the PDCP layer and the RLClayer; performs processes such as user data IP packet headercompression, data encoding, and segmentation and concatenation of data;and adjusts the data size. The data generation part 201 outputs theprocessed data and logical channel information on the data to thetransmission data storage part 203.

The transmission data storage part 203 accumulates, for each user, thedata input from the data generation part 201, and in accordance with aninstruction from the MAC control part 217, outputs the specified data tothe transmission processing part 205 by the specified data volume. Thetransmission data storage part 203 also outputs information regardingthe volume of accumulated data to the MAC control part 217.

The transmission processing part 205 codes the data input from thetransmission data storage part 203, and performs a puncture process onthe coded data. Then, the punctured data is modulated and coded. Thetransmission processing part 205 maps the modulated and coded data tochannels and signals of each cell, such as the physical downlink controlchannel PDCCH, downlink synchronization signal, physical broadcastchannel PBCH, and physical downlink shared channel PDSCH, performs OFDMsignal processing, such as serial/parallel conversion, inverse fastFourier transform (IFFT) conversion, CP insertion, and the like, on themapped data, and generates an OFDM signal.

The transmission processing part 205 then outputs the generated OFDMsignal to the radio part 207. Upon having received a responseinstruction to received data from the MAC control part 217, thetransmission processing part 205 generates an ACK or a NACK signal, mapsthe generated signal on the physical downlink control channel PDCCH, andoutputs the signal to the radio part 207.

The radio part 207 upconverts the data input from the transmissionprocessing part 205 to a radio frequency, adjusts the transmit power,and transmits the data from a transmit antenna. The radio part 207downcoverts radio signals received via a receive antenna, and outputsthe signals to the reception processing part 209. The receptionprocessing part 209 performs a fast Fourier transform (FFT) process,coding, a demodulation process, and the like on the signals input fromthe radio part 207.

The reception processing part 209 decodes the physical uplink sharedchannel PUSCH data in the demodulated data. Upon succeeding in decodingthe data, the reception processing part 209 outputs the data to the MACinformation extraction part 211. The reception processing part 209 alsooutputs, to the MAC control part 217, downlink transmission dataresponse information (ACK/NACK) on control data acquired from thephysical uplink control channel PUCCH in the demodulated data, downlinkradio quality information (CQI), and uplink transmission requestinformation (scheduling request).

Upon detection of a random access preamble, the reception processingpart 209 calculates transmission timing from the detected random accesspreamble, and outputs the detected random access preamble number and thecalculated transmission timing, to the MAC control part 217. Thereception processing part 209 calculates the transmission timing from anuplink reference signal, and outputs the calculated transmission timingto the MAC control part 217.

The MAC information extraction part 211 extracts the MAC layer controldata from data input from the reception processing part 209, and outputsthe extracted control information to the MAC control part 217. The MACinformation extraction part 211 outputs the remaining data to the dataprocessing part 213. The data processing part 213 has functions of thePDCP layer and the RLC layer, performs processing, such as an expansion(decompression) function for compressed IP headers, a decoding functionfor encoded data, and segmentation and concatenation of data, to restorethe data to the original form thereof. The data processing part 213divides the data into an RRC message and user data, and outputs the RRCmessage to the RRC control part 219, and outputs the user data to thehigher layer.

The MAC control part 217 has functions of the MAC layer, and controlsthe MAC layer on the basis of information acquired from the RRC controlpart 219, the lower layer, and the like. The MAC control part 217performs downlink and uplink scheduling processes. The MAC control part217 performs downlink and uplink scheduling processes on the basis ofresponse information on the downlink transmission data (ACK/NACK), thedownlink radio quality information (CQI), and the uplink transmissionrequest information (scheduling request) which have been input from thereception processing part 209, the control information input from theMAC information extraction part 211, and data volume information foreach user acquired from the transmission data storage part 203, and thereception operation state of the terminal device 1-1. The MAC controlpart 217 outputs the scheduling result to the transmission processingpart 205.

Upon having acquired a random access preamble number and transmissiontiming from the reception processing part 209, the MAC control part 217creates a random access response message, and outputs the random accessresponse message to the transmission data storage part 203. In addition,upon having acquired transmission timing from the reception processingpart 209, the MAC control part 217 creates a transmission timing messageincluding the transmission timing, and outputs the transmission timingmessage to the transmission data storage part 203.

Using the transmission timing timer, the MAC control part 217 managesthe uplink transmission timing of the transmission timing group of theterminal device 1-1. Upon having transmitted a transmission timingmessage of each transmission timing group to the terminal device 1-1,the MAC control part 217 starts or restarts the correspondingtransmission timing timer.

The RRC control part 219 performs various configurations forcommunications with the terminal device 1-1, such as processes ofconnecting with/disconnecting from the terminal device 1-1, and datatransmission control configuration for determining a cell in which thecontrol data and user data of the terminal device 1-1 are transmittedand received; exchanges information with the higher layer in associationwith the various configurations; and controls the lower layer inassociation with the various configurations.

The RRC control part 219 creates RRC messages of each type, and outputsthe created RRC messages to the data generation part 201. The RRCcontrol part 219 analyzes RRC messages input from the data processingpart 213.

Furthermore, the RRC control part 219 also outputs information necessaryfor the MAC layer to the MAC control part 217, and outputs informationnecessary for the physical layer to the PHY control part 215. Uponhaving notified of the release of the physical uplink control channelPUCCH or uplink sounding reference signal from the MAC control part 217,the RRC control part 219 releases the assigned physical uplink controlchannel PUCCH and uplink sounding reference signal, and instructs thePHY control part 215 to release the physical uplink control channelPUCCH and the uplink sounding reference signal.

In addition, the RRC control part 219 configures information about thenumber of transmission/reception repetitions (the number of receptionrepetitions, the number of transmission repetitions), on the basis of ameasurement report message from the terminal device 1-1, and/or uplinkradio quality information from the reception processing part 209. Thatis, for each terminal device 1-1, the RRC control part 219 configuresthe number of reception repetitions for the PDSCH, PDCCH, EPDCCH,MPDCCH, and the like, and the number of transmission repetitions for thephysical uplink shared channel PUSCH and physical uplink control channelPUCCH, performed by the terminal device 1-1. The number oftransmission/reception repetitions may be configured for each uplink anddownlink, or for each physical channel.

The RRC control part 219 creates a repetitive transmission/receptioncontrol message including the aforementioned number oftransmission/reception repetitions, and outputs the repetitivetransmission/reception control message to the transmission data storagepart 203. Furthermore, the RRC control part 219 notifies the MAC controlpart 217 and the PHY control part 215 of the number of receptionrepetitions and the number of transmission repetitions that have beenconfigured for the terminal devices 1-1. The repetitivetransmission/reception control message may be, for example, an RRCreconfiguration message, or a new RRC message. One or multiple controlparts may be constituted of some or all of the transmission processingpart 205, the radio part 207, the reception processing part 209, the MACcontrol part 217, and the RRC control part 219.

Note that the transmission processing part 205, the radio part 207, andthe reception processing part 209 perform physical layer operations; thetransmission data storage part 203, the MAC information extraction part211, and the MAC control part 217 performs MAC layer operations, thedata generation part 201 and the data processing part 213 performs RLClayer and PDCP layer operations, and the RRC control part 219 performsRRC layer operations. In FIG. 2, other constituent elements of the basestation device 3, and data (control information) transmission pathsamong constituent elements have been omitted, but it is obvious that thebase station device 3 includes, as constituent elements thereof,multiple blocks having other functions necessary for operating as thebase station device 3. For example, a radio resource management part andan application layer part are present above the RRC control part 219.

Terminal devices 1-1 may be classified into two or three types. Forexample, terminal devices of the first type are terminals classified ascategory 0 to category 13, or the like. It may also be said that theterminals are not for MTC. Terminals of the second type have alimitation on a support system bandwidth in downlink due to lower incost. The terminals of the second type include a certain level ofcoverage enhancement (cell enhancement). The terminals of the secondtype may be classified as category (−1) or the like. Terminals of thethird type are terminals that support coverage enhancement. Theterminals of the third type may be classified as category (−2) or thelike. That is, the maximum number of repetitions supported by theterminal devices of the second type may be fewer than that supported bythe terminal devices of the third type. The functions supported by therespective types differ, and the application of the types need not belimited to MTC. Also, the second type and the third type may becollectively considered as the second type, and distinguished in termsof function from the first type.

Next, in the present embodiment, cell selection performed by theterminal device 1-1 will be described.

The terminal device 1-1 scans, on the basis of the capability thereof,an RF channel of an EUTRA frequency band. At this time, the terminaldevice 1-1 may scan the RF channel with reference to cell selectioninformation (frequency or cell information) held in the terminal device1-1. Furthermore, the terminal device 1-1 may attempt cell selectionwith a fewer number of repetitions. Upon failure in cell selection, theterminal device 1-1 may attempt cell selection with a larger number ofrepetitions.

The terminal device 1-1 searches for a cell having the largest power ineach carrier frequency, and once a suitable cell has been found, selectsthat cell. Here, the “suitable cell” refers to a certain cell of aselected PLMN, registered PLMN, or PLMN in an equivalent PLMN list, acertain cell in at least one tracking area, the cell being not barredand the tracking area being not included in a list of forbidden trackingareas for roaming, and a cell satisfying a selection criteria discussedbelow.

Upon having found a cell, the terminal device 1-1 determines, on thebasis of information such as the broadcast information or receive powerof the cell, whether access to the cell is permitted, and whether thecell selection criteria are satisfied. For example, informationindicating whether or not the cell is a barred cell may be included insystem information acquirable by the terminal device 1-1 of the firsttype (e.g., information broadcast with being included in systeminformation block type 1 (SystemInformationBlockType1)), or informationindicating whether or not the cell is a barred cell for the terminaldevices 1-1 (MTCUE) of the second type and third type may be included innew system information for the terminal devices 1-1 of the second typeand third type (e.g., information broadcast with being included insystem information block type 1A (SystemInformationBlockType1A)).

Additionally, a parameter for determining whether cell selectioncriteria are satisfied (e.g., the minimum required reception level(Qrxlevmin), the minimum required quality level (Qqualmin), offset addedto Qrxlevmin and Qqualmin (Qrxlevminoffset and Qqualminoffset,respectively), or the like) may be included in system informationacquirable by the terminal device 1-1 of the first type (e.g.,information broadcast with being included in system information blocktype 1 (SystemInformationBlockType1)), may be included in systeminformation for the terminal devices 1-1 of the second type and thirdtype (e.g., information broadcast with being included in systeminformation block type 1A (SystemInformationBlockType1A)), or may beincluded in both.

For example, the terminal device 1-1 of the first type may use aparameter included in the SystemInformationBlockType1, and the terminaldevices 1-1 of the second type and third type may use a new parameterincluded in the SystemInformationBlockType1A. In this case, the newsystem information may include an independent parameter for each of thenumbers of repetitions (repetition level, cell enhancement level).Furthermore, in this case, all of the parameters may be independent foreach of the number of repetitions (repetition level, cell enhancementlevel), or only some of the parameters may be independent. In addition,only parameters based on the maximum number of repetitions (repetitionlevel, cell enhancement level) supported by the base station device 3rather than values that are independent for each of the number ofrepetitions (repetition level, cell enhancement level) may be broadcastto the terminal devices 1-1 of the second type and third type (terminaldevices supporting cell enhancement).

From the value obtained by subtracting Qrxlevmin and Qrxlevminoffsetfrom the measured reception level (RSRQ), the terminal device 1-1subtracts the larger value of 0 decibels and the value obtained bysubtracting the maximum RF output power of the terminal device 1-1 fromthe maximum transmit power level during uplink transmission, to obtainthe result as Srxlev.

Furthermore, the terminal device 1-1 takes the value obtained bysubtracting Qqualmin and Qqualminoffset from the measured quality level(RSRQ), as Squal.

The terminal device 1-1 takes, as cells satisfying the cell selectioncriteria, cells having Srxlev greater than zero and Squal greater thanzero.

Next, in the present embodiment, cell reselection performed by theterminal device 1-1 will be described. Note that the terminal device 1-1need not have some or all of cell reselection functions. For example,the terminal device 1-1 may lack a function of reselecting a cell ofdifferent frequency, and have only a function of reselecting a cellwithin the same frequency.

When serving cell (PCell) broadcast information includes information onoffset to a neighbor cell, information on offset to a frequency of theneighbor cell, or a hysteresis value for preventing frequent cellreselection, the terminal device 1-1 acquires this information. Next,the terminal device 1-1 calculates a value (Rs) obtained by adding thehysteresis value to the reception level (RSRP) of the serving cell(PCell). The terminal device 1-1 also calculates a value (Rn) obtainedby subtracting the offset from the reception level (RSRP) of a neighborcell(s). The terminal device 1-1 compares the calculated Rs and the Rnof one or more neighbor cells, and selects a cell for reselection.

Note that the terminal device 1-1 may be configured to performmeasurement for reselection, when the reception level (RSRP) or qualitylevel (RSRQ) of the serving cell (PCell) is equal to or less than apredetermined threshold value. At this time, the measurement may beperformed only when the number of repetitions (repetition level, cellenhancement level) configured for the terminal device 1-1 is equal tothe maximum number in the serving cell (PCell); or the measurement maybe performed even when the number of repetitions (repetition level, cellenhancement level) configured for the terminal device 1-1 is not equalto the maximum number in the serving cell (PCell), and when no cell tobe reselected has not been found, the number of repetitions may bechanged by the method described below.

Next, in the present embodiment, a method of configuring the number oftransmission repetitions and the number of reception repetitions at thetime of initial random access performed by the terminal device 1-1 willbe described with reference to FIG. 3.

First, the terminal device 1-1 acquires system information of the basestation device 3 from the physical broadcast channel PBCH or the like(step S301). The system information may be transmitted (broadcast) by apredetermined number of repetitions. Alternatively, only part of thesystem information may be transmitted (broadcast) by the predeterminednumber of repetitions, and the other part of the system informationexcluding the part of the system information may be transmitted(broadcast) by the number of repetitions notified through the part ofthe system information, the number of repetitions of PDSCH whose systeminformation is included in a downlink control channel (PDCCH, EPDCCH,MPDCCH, and the like) may be specified, or a combination thereof mayalso be acceptable.

With the way described above, the terminal device 1-1 acquiresinformation about the number of repetitions, and acquires informationrelating to the random access procedure included in the systeminformation. The information relating to the random access procedure isconstituted of physical random access channel PRACH mapping information,random access preamble generation information, random access preambleselection information, information relating to random access responsereception, information relating to message 3 transmission, informationrelating to contention resolution message reception, and the like.

The terminal device 1-1 selects a random access preamble from the randomaccess preamble selection information (step S302). Using a physicalrandom access channel PRACH resource, the terminal device 1-1 transmitsthe random access preamble (step S303). Here, the terminal device 1-1may determine the number of transmission repetitions of the randomaccess preamble on the basis of a path-loss value or the received power(RSRP or the like) of the signal received from the base station device3; may determine the number on the basis of the number of receptionrepetitions required for acquiring the PBCH or other system information;may determine the number on the basis of the downlink radio quality andinformation relating to the number of transmission repetitions acquiredfrom the system information; or may initially start transmission withthe minimum number of repetitions, and upon failure in transmission,increase the number of repetitions.

The terminal device 1-1 may perform transmission using a random accesspreamble and/or PRACH resource that has been associated with the numberof transmission repetitions. The random access preamble is transmittedwith the same transmit power, up to the number of transmissionrepetitions for preamble transmission. Note that random access preambleselection information may also be constituted of information relating toa random access preamble selected by a mobile station device, andinformation relating to a random access preamble selected by theterminal device 1-1.

The base station device 3 detects the random access preamble transmittedfrom the terminal device 1-1. Here, the base station device 3 maydetect, by the number of reception repetitions predefined in the system,the random access preamble transmitted from the terminal device 1-1, orconfigure the number of reception repetitions on the basis of the randomaccess preamble and/or PRACH resource to be used and detect the randomaccess preamble transmitted from the terminal device 1-1.

The base station device 3 calculates the shift in transmission timingbetween the terminal device 1-1 and the base station device 3 from thedetected random access preamble, performs scheduling (specification ofan uplink radio resource position (position of the uplink shared channelPUSCH), a transmission format (message size), and the like) fortransmitting a Layer 2 (L2)/Layer 3 (L3) message, assigns a temporarycell-radio network temporary identity (C-RNTI: terminal deviceidentification information), and transmits a random access responsemessage. The base station device 3 may map, on the physical downlinkcontrol channel PDCCH, EPDCCH, or MPDCCH, a random access-radio networktemporary identity (RA-RNTI: random access response identificationinformation) indicating a response (random access response) addressed tothe terminal device 1-1 that has transmitted the random access preambleof the random access channel RACH, and transmits, on the physicaldownlink shared channel PDSCH, a random access response messageincluding transmission timing information, scheduling information, atemporary C-RNTI, and the received random access preamble information;or transmits a random access response message using a downlink radioresource that has been uniquely associated beforehand with a randomaccess preamble and/or PRACH resource. At this time, the number oftransmission repetitions of the random access response message may bespecified through the PDCCH, EPDCCH, or MPDCCH on which the RA-RNTI ismapped, may be a predetermined number of repetitions, or may be thenumber of repetitions associated with the detected random accesspreamble and/or PRACH resource. The random access response message isrepeatedly transmitted on the physical downlink shared channel PDSCH.

The terminal device 1-1 receives the random access response message andverifies the content thereof (step S305). At this time, the number ofreception repetitions of the random access response message may bespecified through the PDCCH, EPDCCH, or MPDCCH on which the RA-RNTI ismapped, may be a predetermined number of repetitions, or may be thenumber of repetitions associated with the random access preamble and/orPRACH resource that has been last transmitted by the terminal deviceitself in step S304. Furthermore, the terminal device 1-1 may receivethe physical downlink shared channel PDSCH in a downlink resource regionuniquely associated with the random access preamble and/or with aphysical random access channel resource (mapping information), anddetect a random access response message.

When a random access response message includes information about thetransmitted random access preamble, the terminal device 1-1 adjusts theuplink transmission timing on the basis of the transmission timinginformation, and transmits an L2/L3 message that includes informationidentifying the terminal device 1-1, such as the C-RNTI (or temporaryC-RNTI), an international mobile subscriber identity (IMSI), or thelike, with the scheduled radio resource and transmission format (stepS307). At this time, the number of transmission repetitions fortransmission of this message, which is configured in step S306, may be apredetermined number of repetitions, may be the number of repetitionsspecified in the random access response message, or may be the number ofrepetitions equal to that of the random access preamble last transmittedby the device itself. The terminal device 1-1 repeatedly transmits themessage 3 up to the configured number of transmission repetitions.

Furthermore, when the transmission timing has been adjusted, theterminal device 1-1 starts the transmission timing timer.

Upon receiving the L2/L3 message from the terminal device 1-1, the basestation device 3, using the C-RNTI (or temporary C-RNTI) or the IMSIincluded in the received L2/L3 message, transmits, to the terminaldevice 1-1, a contention resolution message for determining whethercontention (collision) is occurring among terminal devices 1-1 to 1-3.The number of transmission repetitions of the contention resolutionmessage may be specified through the PDCCH, EPDCCH, or MPDCCH on whichis mapped the C-RNTI indicating that the information is addressed to theterminal device 1-1; may be a predetermined number of repetitions; maybe the number of repetitions associated with the random access preambleand/or PRACH resource; may be the number of repetitions equal to that ofthe random access response message; or may be the number of repetitionsconfigured for the terminal device 1-1 in the random access responsemessage.

The terminal device 1-1 receives the contention resolution message (stepS309). At this time, the number of reception repetitions of thecontention resolution message, which is configured in step S308, may bespecified through the PDCCH, EPDCCH, or MPDCCH on which is mapped theC-RNTI indicating that information is addressed to the terminal deviceitself; may be a predetermined number of repetitions; may be the numberof repetitions associated with the random access preamble and/or PRACHresource; may be configured to be the number of repetitions equal tothat of the random access response message; or may be configured to bethe number of repetitions configured in the random access responsemessage.

Note that when a random access response message that includes a preamblenumber corresponding to the random access preamble transmitted by theconfigured number of transmission repetitions has not been detectedwithin a specified period of time, transmission of the message 3 hasfailed, or identification information on the terminal device 1-1 itselfhas not been detected in the contention resolution message within aspecified period of time, the terminal device 1-1 starts the processover from transmission of the random access preamble. When doing so, thenumber of repetitions of the random access preamble may be increased.Then, when the number of transmissions of the random access preamble hasexceeded the maximum number of transmissions of the random accesspreamble indicated by the system information, the terminal device 1-1determines that the random access has failed.

The number of transmission repetitions of the physical uplink sharedchannel PUSCH or the number of reception repetitions of the physicaldownlink shared channel PDSCH after completion of the random accessprocedure may be configured to correspond to the random access preamble.Furthermore, the number of transmission repetitions or receptionrepetitions after completion of the random access procedure may beindividually notified to the terminal device 1-1 through the systeminformation. Notification may also be made via the random accessresponse message or contention resolution message of the random accessprocedure described earlier. For example, the information about thenumber of transmission repetitions and reception repetitions for eachchannel may be defined as a plurality of sets, or may be broadcast fromthe base station device 3 as the system information, and the informationindicating which set the terminal device 1-1 employs may correspond tothe random access preamble used (the number of transmission repetitionsof the random access preamble), may be notified through the randomaccess response message or contention resolution message, may benotified through another RRC message or MAC control element as aseparate configuration, or may be a combination thereof.

Next, a method of changing the number of repetitions with the terminaldevice 1-1 in an RRC connected state will be described.

As the method of changing the number of repetitions, one conceivablemethod involves the base station device 3 notifying of a change in thenumber of repetitions, on the basis of a report from the terminal device1-1.

For example, the base station device 3 may configure the number ofrepetitions for uplink or the number of repetitions for downlink withrespect to the terminal device 1-1 on the basis of the power of a signalreceived from the terminal device 1-1, or the measurement result of thedownlink channel state information (CQI), downlink reference signalreceived power (RSRP) and received quality (RSRQ), or the like that arenotified by the terminal device 1-1, and notify the terminal device 1-1of this number. In the method of notification to the terminal device1-1, notification may be made through a message in the RRC layer (e.g.,an RRC connection re-establishment message or a new RRC message),notification may be made through control information in the MAC layer (aMAC control element), or notification may be made in the form ofdownlink control information or uplink control information in the PHYlayer. The terminal device 1-1 may run a timer at a specific measurementreport timing triggered when the received quality or received power ofthe serving cell (PCell) is lower than a threshold value, and when thenumber of repetitions satisfying a condition has not been configured bythe base station device 3 before the timer expires, initiate aconnection re-establishment procedure, or transition to an idle state.This configuration causes the timer to stop upon the number ofrepetitions satisfying the condition having been configured before thetimer expires.

As another method, a method in which the terminal device 1-1 changes thenumber of repetitions (and/or notifies the base station device 3) on thebasis of the state thereof is conceivable.

For example, upon failing to transmit and/or receive with the number ofrepetitions configured in the terminal device 1-1 (when a greater numberof repetitions is required), the terminal device 1-1 regards, on thebasis of a configuration condition of the number of repetitions whichhas been configured or notified in advance, the event as a radio linkfailure at the point in time of change in the number of repetitions(preferably only in cases of change to a greater number of repetitions),and attempts to reconfigure the RRC connection.

Furthermore, for example, upon failing to transmit and/or receive usingthe number of repetitions configured in the terminal device 1-1 (when agreater number of repetitions is required), the terminal device 1-1 maytransition, on the basis of a configuration condition of the number ofrepetitions which has been configured or notified in advance, to an idlestate at the point in time of change in the number of repetitions(preferably only in cases of change to a greater number of repetitions).Upon having data for transmission therein, having received paging,performing location registration, or the like, the terminal device 1-1may start from the initial random access procedure, in order toestablish an RRC connection.

Furthermore, for example, on the basis of the measurement result of thereceived level (RSRP) of the serving cell (PCell), the received level,and a configuration condition of the number of repetitions which hasbeen configured or notified in advance, the terminal device 1-1 may makenotification (or request) of a change in the number of repetitions(repetition level, cell enhancement level) by the random accessprocedure described below, at the point in time of change in the numberof repetitions (preferably only in cases of change to a greater numberof repetitions).

The terminal device 1-1 may configure the period for performingmeasurement of the reference signal received power (RSRP) as describedabove such that the period differs depending on the number ofrepetitions (repetition level, cell enhancement level). For example, theterminal device 1-1 may configure the period for measurement of the samefrequency as that of the serving cell (PCell) to be 200 ms when thenumber of repetitions is zero (state of no cell enhancement), and thenincrease the measurement period from 200 ms as the number of repetitions(repetition level, cell enhancement level) increases. The measurementperiod at the time of cell enhancement may be one for which the periodis predefined to correspond to the number of repetitions; the period maybe derived from the number of repetitions by a computational expression;or the period may be notified and configured through broadcastinformation or an individual RRC message to the terminal device 1-1.

The terminal device 1-1 may perform radio link monitoring (RLM) in orderto detect reception failure such as that described above. The radio linkmonitoring performed by the terminal device 1-1 will be described below.

For the radio link monitoring in the terminal device 1-1, the PHYcontrol part 115 notifies, on the basis of information such as thereference signal received power measured by the reception processingpart 109, the higher layer (the RRC control part 119) of an“out-of-sync” condition when it is estimated that the radio link qualityof the serving cell (PCell) is continuously equal to or less than aspecific threshold value (Qout) for longer than a specific period (e.g.,T_(Evaluate) Q_(out)=200 ms). The PHY control part 115 also notifies, onthe basis of information such as the reference signal received powermeasured by the reception processing part 109, the higher layer (the RRCcontrol part 119) of an “in-sync” condition when it is estimated thatthe radio link quality of the serving cell (PCell) is continuously equalto or greater than a specific threshold value (Qin) for longer than aspecific period (e.g., T_(Evaluate) Q_(in)=100 ms). It is preferablethat the PHY control part 115 notify the higher layer of the out-of-syncor in-sync condition at specific intervals (e.g., T_(Report sync)=10ms).

Here, for example, the threshold value Qout is defined as the level atwhich the downlink radio link cannot be reliably received and shallcorrespond to 10% block error rate of a hypothetical downlink controlchannel transmission based on previously defined parameters (or, incases in which the terminal device 1-1 is a terminal of a specific type(e.g., a second type or third type), transmission that includes (takesinto account) the repeated transmission (bundling size) configured inthe terminal device 1-1). Furthermore, for example, the threshold valueQin is defined as the level at which the downlink radio link quality canbe significantly more reliably received than in the Qout state and shallcorrespond to 2% block error rate of a hypothetical downlink controlchannel transmission based on previously defined parameters (or, incases in which the terminal device 1-1 is a terminal of a specific type(e.g., a second type or third type), transmission that includes (takesinto account) the repeated transmission (bundling size) configured inthe terminal device 1-1).

When out-of-sync conditions have been consecutively received apredetermined number of times (N310 times), the higher layer (the RCCcontrol part 119) starts or restarts the running of the timer (T310).When in-sync conditions have been consecutively received a predeterminednumber of times (N311 times), the RCC control part 119 stops the runningof the timer (T310). When the running of the timer (T310) has expiredwithout stopping, the RRC control part 119 may transition to an idlestate, or perform an RRC connection re-establishment procedure.

The foregoing is an example of a case in which DRX has not beenconfigured in the terminal device 1-1, but when DRX has been configuredin the terminal device 1-1, the RRC control part 119 may configure theperiod for measuring radio link quality, or the interval of notificationto the higher layer, so that these have different values than when DRXhas not been configured. Even when DRX has been configured and theaforementioned timer (T310) is running, the period for measuring radiolink quality for estimating the in-sync condition, or the interval ofnotification to the higher layer may be the same values as when DRX hasnot been configured.

Some or all of the parameters of timer (T310), threshold values (Qin,Qout), number of times (N310, N311), periods (T_(Evaluate) Q_(out),T_(Evaluate) Q_(in)), or interval (T_(Report sync)) may be values thatare configured individually for each of the number of repetitions(repetition level, cell enhancement level), or other valuescorresponding to cell enhancement. The values may be predeterminedvalues; may be broadcast by the base station device 3 through broadcastinformation which is system information directed to a terminal device ofa certain type for example; may be individually configured for theterminal device 1-1 through an RRC message or the like; or may be acombination thereof.

For parameters such as timers, threshold values, number of times, andthe like, different values for the same parameter may be configured forterminal devices of a certain type, and terminal devices of other types.When doing so, values may be selected from alternatives that differbetween terminal devices of a certain type, and terminal devices ofother types. For example, as the range of values that can be assumed bya timer such as T310, a range of 0 ms to 2000 ms can be selected forterminal devices not compatible with cell expansion, and a range of 0 msto T ms (T>2000) can be selected for terminal devices compatible withcell expansion. By so doing, it is possible to introduce terminaldevices compatible with cell expansion while reducing the effects onexisting procedures.

For parameters such as timers, threshold values, number of times, andthe like, values may be configured for new parameters which areindependent of the parameters of terminal devices not compatible withcell enhancement, and when doing so, the values can be selected fromalternatives having different value ranges with respect to theindependent parameters.

This enables the terminal device 1-1 to acquire new system information,different from system information for terminal devices of the first type(terminal devices not compatible with cell enhancement), from broadcastinformation that is directed to terminal devices of the second type andthird type (terminal devices compatible with cell enhancement), andperform appropriate radio link monitoring, by configuring radio linkmonitoring parameters according to the number of repetitions (repetitionlevel, cell expansion level) of the terminal device 1-1.

On the basis of parameters and the values thereof, the terminal device1-1 may also derive the number of repetitions that brings the terminaldevice 1-1 into in-sync.

On the basis of the radio link monitoring and the like discussed above,when a reception fails (when an out-of-sync condition is notified apredetermined number of times, when the timer T310 has expired, or thelike), the terminal device 1-1 may notify the base station device 3 ofthe change in the number of repetitions (or of the need for a change inthe number of repetitions) by carrying out random access as describedbelow.

An example of a method of configuring the number of repetitions when arandom access procedure is to be performed in the RRC connected statewill be described with reference to FIG. 4.

The terminal device 1-1 may be configured to hold information in whichthe number of repetitions and threshold values for received power orreceived quality are associated with each other as predeterminedinformation, or acquire such information from the base station device 3as an RRC layer message. For example, the information may take the formof a table constituted of multiple numbers of transmission and receptionrepetitions, and threshold values for downlink reference signal receivedpower (RSRP) or received quality (RSRQ) associated with the numbers ofrepetitions; or the form of a table constituted of the number ofrepetitions, and threshold values of block error rate (BLER) associatedwith the numbers of repetitions. Alternatively, the terminal device 1-1may hold one or more sets of information indicating the number ofrepetitions, either as a predetermined configuration or a configurationnotified through an RRC layer message from the base station device 3;and further, information indicating which number of repetitions is valid(an index uniquely corresponding to information indicating the number ofrepetitions, or the like) may be notified to the terminal device 1-1from the base station device 3, in the form of an RRC layer message, asa MAC layer control element, or as downlink control information of thephysical layer. The numbers of repetitions may be configuredindependently for each physical channel in the tables and information.

When there has been a change in the number of repetitions on the basisof information, data demodulation has failed during a fixed time period(or a fixed number of times), or the like, the terminal device 1-1notifies (or reports) the change in the number of repetitions to thebase station device 3, through random access. When the number ofrepetitions changes in the decreasing direction, the current number ofrepetitions may be maintained until a new configuration is made by thebase station device 3. That is, the terminal device 1-1 may makenotification to the base station device 3 only when the number ofrepetitions changes in the increasing direction.

In order to make notification to the base station device 3, the MACcontrol part 117 may release the PUCCH resource that has been assignedto the terminal device itself, may notify the RRC layer of the releaseof the PUCCH resource, or may stop the TA timer. That is, the MACcontrol part 117 may bring the system into a state in which uplinktransmission other than random access preamble transmission does nottake place, and notify the base station device 3 of a change in thenumber of repetitions (or a re-configured number of repetitions) througha random access procedure. Also, when the TA timer has stopped orexpired, the terminal device 1-1 may release the configuration of thenumber of transmission repetitions (or the index information indicatingwhich number of transmission repetitions) configured therein.

From random access-related information included in the systeminformation or in information configured individually for the terminaldevice 1-1, the terminal device 1-1 generates a random access preamble(step S401). Using the random access channel PRACH resource, theterminal device 1-1 then transmits the random access preamble (stepS402). Here, the terminal device 1-1 may employ, as the number oftransmission repetitions of the random access preamble, the number ofrepetitions already configured therein; or when the configuration of thenumber of transmission repetitions configured in the terminal device 1-1has been released, may determine the number of transmission repetitionsof the random access preamble from the measured value, such as thepath-loss value or received power (RSRP or the like) of a signalreceived from the base station device 3, and from a threshold valueassociated with the number of repetitions; or may employ a predeterminednumber of repetitions.

The terminal device 1-1 may acquire (derive) information about thenumber of repetitions by using the way described above, and transmit thesame using a PRACH resource and/or a random access preamble associatedwith the number of repetitions at the time of transmission.

The base station device 3 detects the random access preamble transmittedfrom the terminal device 1-1. Here, the base station device 3 may detectthe random access preamble transmitted from the terminal device 1-1 byusing the number of reception repetitions predefined in the system, ormay configure the number of reception repetitions with the random accesspreamble and/or PRACH resource used, and detect the random accesspreamble from the terminal device 1-1.

The base station device 3 calculates the shift in transmission timingbetween the terminal device 1-1 and the base station device 3 from thedetected random access preamble, performs scheduling (specification ofan uplink radio resource position (position of the physical uplinkshared channel PUSCH), a transmission format (message size), and thelike) for transmitting a Layer 2 (L2)/Layer 3 (L3) message, assigns atemporary cell-radio network temporary identity (C-RNTI: terminal deviceidentification information), and transmits a random access responsemessage. The base station device 3 may map, on the physical downlinkcontrol channel PDCCH, EPDCCH, or MPDCCH, a random access-radio networktemporary identity (RA-RNTI: random access response identificationinformation) indicating a response (random access response) addressed tothe terminal device 1-1 that has transmitted the random access preambleon the random access channel RACH, and transmit, on the physicaldownlink shared channel PDSCH, a random access response messageincluding transmission timing information, scheduling information, atemporary C-RNTI, and the received random access preamble information;or may transmit a random access response message with a physicaldownlink shared channel PDSCH radio resource that has been associatedbeforehand with a random access preamble and/or PRACH resource. At thistime, the number of transmission repetitions of the random accessresponse message may be specified through the PDCCH, EPDCCH, or MPDCCHon which the RA-RNTI is mapped, may be a predetermined number ofrepetitions, or may be the number of repetitions associated with thedetected random access preamble and/or PRACH resource. Also, when therandom access procedure is a non-contention based random accessprocedure, the base station device 3 may configure the number oftransmission repetitions to be the number of transmission repetitionsconfigured in the terminal device 1-1.

The terminal device 1-1 receives the random access response message andverifies the content thereof (step S404). At this time, the number ofreception repetitions of the random access response message may bespecified through the PDCCH, EPDCCH, or MPDCCH on which the RA-RNTI ismapped, may be a predetermined number of repetitions, or may be thenumber of repetitions associated with the random access preamble and/orPRACH resource last transmitted by the terminal device itself in stepS403. Also, when the random access procedure is a non-contention basedrandom access procedure, the terminal device 1-1 may configure thenumber of reception repetitions of the random access response message tobe the number of reception repetitions configured therein.

Additionally, when the configuration information on the number ofrepetitions has been included in the random access response message, theterminal device 1-1 may overwrite the configuration of the number ofrepetitions configured therein, with the received configurationinformation. Alternatively, when the configuration information on thenumber of repetitions has been included in the random access responsemessage, the terminal device 1-1 may discard or ignore the configurationof the number of repetitions configured therein, and use the receivedconfiguration information.

When a random access response message includes information about thetransmitted random access preamble, the terminal device 1-1 adjusts theuplink transmission timing on the basis of the transmission timinginformation, and transmits an L2/L3 message that includes informationidentifying the terminal device 1-1, such as the C-RNTI (or temporaryC-RNTI), the international mobile subscriber identity (IMSI), or thelike, using the scheduled radio resource and transmission format (stepS406). At this time, the number of transmission repetitions fortransmission of this message, which is configured in step S405, may be apredetermined number of repetitions, may be the number of repetitionsspecified in the random access response, or may be the number ofrepetitions equal to that of the random access preamble last transmittedby the terminal device itself.

When the transmission timing has been adjusted, the terminal device 1-1starts a transmission timing timer.

Upon receiving the L2/L3 message from the terminal device 1-1, the basestation device 3, using the C-RNTI (or temporary C-RNTI) or the IMSIincluded in the received L2/L3 message, transmits, to the terminaldevice 1-1, a contention resolution message for determining whethercontention (collision) is occurring among terminal devices 1-1 to 1-3.The number of transmission repetitions of the contention resolutionmessage may be a predetermined number of repetitions, may be the numberof repetitions associated with the random access preamble and/or PRACHresource, or may be the same number of repetitions as the random accessresponse message. Furthermore, an RRC message for re-configuring thenumber of repetitions may be included in the contention resolutionmessage. The information on the number of repetitions may be specifiedthrough the PDCCH, EPDCCH, or MPDCCH on which the C-RNTI indicating thatthe information is addressed to the terminal device 1-1 is mapped.

The terminal device 1-1 receives the contention resolution message (stepS408). The number of reception repetitions of the contention resolutionmessage may be specified through the PDCCH, EPDCCH, or MPDCCH on whichis mapped the C-RNTI indicating that information is addressed to theterminal device itself; may be a predetermined number of repetitions;may be configured to be the number of repetitions associated with therandom access preamble and/or PRACH resource in step S407; or may beconfigured to be the same number of repetitions as the random accessresponse message. Additionally, when some or all of the RRC message forre-configuring the number of repetitions is included in the contentionresolution message, the terminal device 1-1 may overwrite the number ofrepetitions configured therein, with the received configurationinformation.

Note that when a random access response message that includes a preamblenumber corresponding to the transmitted random access preamble has notbeen detected within a specified period of time, when transmission ofthe message 3 has failed, or when identification information on theterminal device 1-1 has not been detected in the contention resolutionmessage within a specified period of time, the terminal device 1-1starts the process over from transmission of a random access preamble.When doing so, the number of repetitions of the random access preamblemay be increased. Also, when doing so, the configuration of the numberof repetitions that is configured in the terminal device itself may bereleased.

Then, when the number of transmissions of the random access preamble hasexceeded the maximum number of transmissions of the random accesspreamble indicated by the system information, the terminal device 1-1determines that the random access has failed, and terminatescommunication with the base station device 3.

When, for example, the random access procedure is performed in a statein which the number of transmission repetitions and/or the number ofreception repetitions has been configured in the terminal device 1-1from the base station device 3 through an RRC message or the like, theabove configuration allows the configuration of the number ofrepetitions to be released prior to transmission of the random accesspreamble and the terminal device 1-1 to configure and use a new numberof repetitions. By so doing, when the state of communication hasdegraded, and even in a state in which a reception signal cannot bereceived from the base station device 3, the terminal device 1-1 itselfis capable of re-configuring the number of repetitions and notifying thechange in the number of repetitions to the base station device 3, andfurther capable of beginning the random access procedure using apredetermined (default, common, or the maximum) number of repetitions,or the number of repetitions based on the measured value of receivedpower or the like, and thus, it is possible to reduce random accessfailures, and it is further possible to re-configure the number ofrepetitions by the base station device 3 through the random accessprocedure.

As another mode, until transmission of the random access preamble ormessage 3, the terminal device 1-1 is capable of using the number ofrepetitions configured therein, and then overwriting the configurationwith the number of repetitions specified through the random accessresponse or contention resolution message. This configuration allows theterminal device 1-1 to notify the base station device 3 of the change inthe number of repetitions, and further allows the base station device 3to reconfigure the number of repetitions through the random accessprocedure.

A configuration is made in which the period during which measurement ofthe terminal device 1-1 is performed can be configured in accordancewith the number of repetitions (repetition level or cell enhancementlevel), which allows appropriate measurements to be performed withoutrelying on the number of repetitions (repetition level or cellenhancement level).

Also, a configuration is made in which a different timer or value of athreshold value can be configured in accordance with the number ofrepetitions (repetition level or cell enhancement level) for measurementof the terminal device 1-1, which allows appropriate measurements to beperformed without relying on the number of repetitions (repetition levelor cell enhancement level).

The first embodiment allows the number of repetitions for efficientrepetitive transmission (or reception) of data to be configured for theterminal device 1-1.

Second Embodiment

A second embodiment of the present invention will be described below.

In the first embodiment, an example has been illustrated in which theterminal device 1-1 in the RRC connected state re-configures the numberof repetitions through the random access procedure. In the presentembodiment, an example will be described in which the terminal device1-1 determines the number of repetitions on the basis of the number ofrepetitions configured therein, and the number of repetitions indicatedin the random access procedure.

In the terminal device 1-1 and the base station device 3 used in thepresent embodiment, some operations of the MAC control part 117 differfrom those in the first embodiment (because operations are added), andtherefore description of the other details will be omitted.

In the present embodiment, when the configuration information on thenumber of repetitions (first information) is included in the randomaccess response message input from the MAC information extraction part111, the MAC control part 117 may notify, on the basis of the firstinformation, the PHY control part 115 of a configuration of the numberof transmission repetitions of the message 3; and when the firstinformation and the information on the number of repetitions notified bythe RRC control part 119 (second information) are compared, and thenumber of repetitions specified in the second information is equal to orgreater than the number of repetitions specified in the firstinformation, the MAC control part 117 may notify, on the basis of thesecond information, the PHY control layer 115 of a configuration of thenumber of reception repetitions of the contention resolution message.Furthermore, the configuration information on the number of repetitionsmay be notified to the RRC control part 119.

In the present embodiment, an example of a method by which the terminaldevice 1-1 changes the number of repetitions in the case of carrying outa random access procedure in the RRC connected state will be describedwith reference to FIG. 5.

The terminal device 1-1 may be configured to hold information in whichthe number of repetitions and threshold values for received power orreceived quality are associated with each other as predeterminedinformation, or acquire such information from the base station device 3as an RRC layer message. For example, the information may take the formof a table constituted of multiple numbers of transmission and receptionrepetitions, and threshold values for downlink reference signal receivedpower (RSRP) or received quality (RSRQ) associated with the numbers ofrepetitions; or the form of a table constituted of the number ofrepetitions, and threshold values of block error rate (BLER) associatedwith the numbers of repetitions. Alternatively, the terminal device 1-1may hold one or more sets of information indicating the number ofrepetitions, either as a predetermined configuration or a configurationnotified through an RRC layer message from the base station device 3;and further, information indicating which number of repetitions is valid(an index uniquely corresponding to information indicating the number ofrepetitions, or the like) may be notified to the terminal device 1-1from the base station device 3, in the form of an RRC layer message, asa MAC layer control element, or as downlink control information of thephysical layer. The numbers of repetitions may be configuredindependently for each physical channel in the tables and information.

When there has been a change in the number of repetitions on the basisof information, data demodulation has failed during a fixed time period(or a fixed number of times), or the like, the terminal device 1-1notifies (or reports) the change in the number of repetitions to thebase station device 3, through random access. When the number ofrepetitions changes in the decreasing direction, the current number ofrepetitions may be maintained until a new configuration is made by thebase station device 3. That is, the terminal device 1-1 may makenotification to the base station device 3 only when the number ofrepetitions changes in the increasing direction.

In order to make notification to the base station device 3, the MACcontrol part 117 may release the PUCCH resource that has been assignedto the terminal device itself, or may stop the TA timer. That is, theMAC control part 117 may bring the system into a state in which uplinktransmission other than random access preamble transmission does nottake place, and notify the base station device 3 of a change in thenumber of repetitions through a random access procedure. Also, when theTA timer has stopped or expired, the terminal device 1-1 may release theconfiguration of the number of transmission repetitions (or the indexinformation indicating which number of transmission repetitions)configured therein.

From random access-related information included in the systeminformation, or in information configured individually for the terminaldevice 1-1, the terminal device 1-1 generates a random access preamble(step S501). Using the random access channel PRACH resource, theterminal device 1-1 then transmits the random access preamble (stepS502). Here, the terminal device 1-1 may employ, as the number oftransmission repetitions of the random access preamble, the number ofrepetitions already configured therein; or when the configuration of thenumber of transmission repetitions configured in the terminal deviceitself has been released, may determine the number of transmissionrepetitions of the random access preamble from the measured value, suchas the path-loss value or received power (RSRP or the like) of a signalreceived from the base station device 3, and from a threshold valueassociated with the number of repetitions; or may employ a predeterminednumber of repetitions.

The terminal device 1-1 may acquire (derive) information about thenumber of repetitions by using the way described above, to transmit thesame using a PRACH resource and/or a random access preamble associatedwith the number of repetitions at the time of transmission.

The base station device 3 detects the random access preamble transmittedfrom the terminal device 1-1. Here, the base station device 3 may detectthe random access preamble transmitted from the terminal device 1-1 byusing the number of reception repetitions predefined in the system, ormay configure the number of reception repetitions with the random accesspreamble and/or PRACH resource used, and detect the random accesspreamble from the terminal device 1-1.

The base station device 3 calculates the shift in transmission timingbetween the terminal device 1-1 and the base station device 3 from thedetected random access preamble, performs scheduling (specification ofan uplink radio resource position (position of the uplink shared channelPUSCH), a transmission format (message size), and the like) fortransmitting a Layer 2 (L2)/Layer 3 (L3) message, assigns a temporarycell-radio network temporary identity (C-RNTI: terminal deviceidentification information), and transmits a random access responsemessage. The base station device 3 may map, on the physical downlinkcontrol channel PDCCH, EPDCCH, or MPDCCH, a random access-radio networktemporary identity (RA-RNTI: random access response identificationinformation) indicating a response (random access response) addressed tothe terminal device 1-1 that has transmitted the random access preambleon the random access channel RACH, and transmit, on the physicaldownlink shared channel PDSCH, a random access response messageincluding transmission timing information, scheduling information, atemporary C-RNTI, and the received random access preamble information;or may transmit a random access response message with a physicaldownlink shared channel PDSCH radio resource that has been associatedbeforehand with a random access preamble and/or PRACH resource. At thistime, the number of transmission repetitions of the random accessresponse message may be specified through the PDCCH, EPDCCH, or MPDCCHon which the RA-RNTI is mapped, may be a predetermined number ofrepetitions, or may be the number of repetitions associated with thedetected random access preamble and/or PRACH resource. Also, when therandom access procedure is a non-contention based random accessprocedure, the base station device 3 may configure the number oftransmission repetitions to be the number of transmission repetitionsconfigured in the terminal device 1-1.

The terminal device 1-1 receives the random access response message andverifies the content thereof (step S504). At this time, the number ofreception repetitions of the random access response message may bespecified through the PDCCH, EPDCCH, or MPDCCH on which the RA-RNTI ismapped, may be a predetermined number of repetitions, or may be thenumber of repetitions associated with the random access preamble and/orPRACH resource last transmitted by the terminal device itself in stepS503. Also, when the random access procedure is a non-contention basedrandom access procedure, the terminal device 1-1 may configure thenumber of repetitions for receiving the PDCCH, EPDCCH, or MPDCCH onwhich the RA-RNTI is mapped, or the number of repetitions for receivingthe PDSCH (random access response message), to be the number ofreception repetitions configured therein. On the other hand, when therandom access procedure is a contention based random access procedure,the terminal device 1-1 may invalidate the configured number ofrepetitions, even when the number of repetitions for receiving thePDCCH, EPDCCH, or MPDCCH on which the RA-RNTI is mapped, or the numberof repetitions for receiving the PDSCH (random access response message),has been configured in the terminal device itself.

When the configuration information on the number of repetitions isincluded in the random access response message, the terminal device 1-1may overwrite the configuration of the number of repetitions configuredtherein, with the received configuration information.

When a random access response message includes information about thetransmitted random access preamble, the terminal device 1-1 adjusts theuplink transmission timing on the basis of the transmission timinginformation, and transmits an L2/L3 message that includes informationidentifying the terminal device 1-1, such as the C-RNTI (or temporaryC-RNTI), the international mobile subscriber identity (IMSI), or thelike, using the scheduled radio resource and transmission format (stepS506). At this time, the number of transmission repetitions fortransmitting this message, which is configured in step S505, may be theconfigured number of repetitions when the number of transmissionrepetitions has been configured in the terminal device itself; or may bea predetermined number of repetitions, or the number of repetitionsequal to that of the random access preamble last transmitted by thedevice itself when the number of transmission repetitions has not beenconfigured in the terminal device itself.

When the transmission timing has been adjusted, the terminal device 1-1starts a transmission timing timer.

Upon receiving the L2/L3 message from the terminal device 1-1, the basestation device 3, using the C-RNTI (or temporary C-RNTI) or the IMSIincluded in the received L2/L3 message, transmits, to the terminaldevice 1-1, a contention resolution message for determining whethercontention (collision) is occurring among terminal devices 1-1 to 1-3.The number of transmission repetitions of the contention resolutionmessage may be the number of repetitions configured in the terminaldevice 1-1 by the base terminal device 3 through an RRC message or thelike; may be a predetermined number of repetitions, may be the number ofrepetitions associated with the random access preamble and/or PRACHresource: or may be the same number of repetitions as the random accessresponse message. Furthermore, an RRC message for re-configuring thenumber of repetitions may be included in the contention resolutionmessage. The information on the number of repetitions may be specifiedthrough the PDCCH, EPDCCH, or MPDCCH on which the C-RNTI indicating thatthe information is addressed to the terminal device 1-1 is mapped.

When the configuration information on the number of repetitions isincluded in the contention resolution message, the terminal device 1-1may overwrite the configuration of the number of repetitions configuredtherein, with the received configuration information. Here, when therandom access procedure is a contention based random access procedureand when the number of repetitions configured in the terminal device 1-1differs from the number of repetitions specified in the contentionresolution message, the terminal device 1-1 may select the number ofrepetitions specified in the contention resolution message.

The terminal device 1-1 receives the contention resolution message (stepS508). The number of reception repetitions of the contention resolutionmessage may be specified through the PDCCH, EPDCCH, or MPDCCH on whichis mapped the C-RNTI indicating that information is addressed to theterminal device itself; may be a predetermined number of repetitions;may be configured to be the number of repetitions associated with therandom access preamble and/or PRACH resource in step S507; or may beconfigured to be the same number of repetitions as the random accessresponse message. When an RRC message for re-configuring the number ofrepetitions is included in the contention resolution message, theterminal device 1-1 overwrites the number of repetitions configuredtherein, with the received configuration information.

Note that when a random access response message that includes a preamblenumber corresponding to the transmitted random access preamble has notbeen detected within a specified period of time, when transmission ofthe message 3 has failed, or when identification information on theterminal device 1-1 itself has not been detected in the contentionresolution message within a specified period of time, the terminaldevice 1-1 starts the process over from transmission of a random accesspreamble. When doing so, the number of repetitions of the random accesspreamble may be increased. Also, when doing so, the configuration of thenumber of repetitions that is configured in the terminal device itselfmay be released.

Then, when the number of transmissions of the random access preamble hasexceeded the maximum number of transmissions of the random accesspreamble indicated by the system information, the terminal device 1-1determines that the random access has failed, and terminatescommunication with the base station device 3.

When, for example, the random access procedure is performed in a statein which the number of transmission repetitions and/or the number ofreception repetitions has been configured in the terminal device 1-1from the base station device 3 through an RRC message or the like, theabove configuration allows the number of repetitions based on the randomaccess preamble or the predetermined configuration to be used for thereception of random access response messages, and allows the number ofrepetitions configured in the terminal device itself to be used for thereception of contention resolution messages. This enables the terminaldevice 1-1 to perform an efficient random access procedure on the basisof the required number of repetitions.

Furthermore, a configuration is made in which the bundling size of thephysical channel (e.g., the PDSCH) can be changed to a different sizeonly in specific cases (e.g., a random access response in a contentionbased random access procedure) can prevent inconsistency from arisingbetween the configuration of the number of repetitions in the terminaldevice 1-1, and the configuration information held by the base stationdevice 3.

The second embodiment allows the number of repetitions for efficientrepetitive transmission (or reception) of data to be configured for theterminal device 1-1 through the random access procedure.

In the preceding embodiments, the functions of the base station device 3may be implemented by other devices. For example, the functions may beimplemented by a relay station device wirelessly connected with the basestation device 3.

Furthermore, in the preceding embodiments, examples have beenillustrated in which the terminal device 1-1 is an MTCUE, as a terminaldevice of a new (enhanced) type (or category) that lacks numerousfunctions (features) such as those of an existing LTE or LTE-advancedterminal device, and has only limited functions (features); however, thepresent invention is not limited these embodiments and can be applied toexisting or future terminal devices (including base station devices andcommunication systems therefor) that are capable of cell enhancement(repetitive transmission/reception).

The embodiments described above are merely exemplary, and can bepracticed using various modifications or substitutions as well. Forexample, it is possible to apply the uplink transmission scheme tocommunication systems of either the frequency division duplex (FDD)scheme or the time division duplex (TDD) scheme. The names of thevarious parameters and events illustrated in the embodiments have beendesignated for convenience in description, and even when designations inactual use and the designations in the embodiments of the presentinvention differ, the spirit of the invention claimed in the embodimentsof the present invention is not affected.

The term “connection” used in the embodiments is not limited exclusivelyto configurations in which a device and another device are directlyconnected using a physical circuit, and includes logically-connectedconfigurations, and wirelessly-connected configurations using radiotechnology.

The terminal devices used in the embodiments may have only one ormultiple parts capable of MAC layer functions (MAC entity). Whenmultiple parts capable of MAC layer functions are present, the wording“configured in each terminal device” means that an identicalconfiguration may be applied to all of the multiple parts capable of theMAC layer functions, or different configurations may be individuallyapplied to the parts capable of the MAC layer functions.

The terminal device 1 includes not only mobile station devices ofportable type or movable type, but also stationary type or non-movabletype electronic devices for indoor/outdoor installation, for example, AVequipment, kitchen appliances, cleaning/laundering appliances, airconditioning equipment, office equipment, vending machines, otherlifestyle devices or measuring devices, and in-vehicle devices, as wellas wearable devices or healthcare devices which can be worn on the bodyand have communication functions incorporated therein. The terminaldevice 1 may be used not just for machine-to-machine communication(Machine Type Communication), but also for person-to-person orperson-to-machine communication.

The terminal device 1 is also referred to as a user terminal, a mobilestation device, a communication terminal, a mobile, a terminal, userequipment (UE), or a mobile station (MS). The base station device 3 isalso referred to as a radio base station device, a base station, a radiobase station, a fixed station, a NodeB (NB), an evolved NodeB (eNB), abase transceiver station (BTS), or a base station (BS).

Note that the base station device 3 is referred to as an NB in UMTS setforth in 3GPP specifications, and as an eNB in EUTRA and Advanced EUTRA.Note that in UMTS, EUTRA, and Advanced EUTRA set forth in 3GPPspecifications, the terminal device 1 is referred to as UE.

For convenience in description, specific combinations of methods, means,or algorithm steps for implementing the functions of the various partsof the terminal devices 1 and base station device 3, or some of thesefunctions, have been described using functional block diagrams; however,these functions can be embodied directly by software modules executed byhardware or processors, or by a combination thereof.

Where implemented using hardware, in addition to the configurations ofthe described block diagrams, the terminal devices 1 and the basestation device 3 may be configured from power supply devices orbatteries for supplying power to the terminal devices 1 and the basestation device 3; liquid crystal or other display devices and displaydriving devices; memory; input/output interfaces and input/outputterminals; speakers; and other peripheral devices.

Where implemented using software, the above-described functions may beheld or transferred in the form of code or one or more commands on acomputer-readable medium. Computer-readable media include both computerrecording media and communication media including media that aid incarrying a computer program from one location to another.

Furthermore, the control of the terminal device 1 and base stationdevice 3 may be performed by recording one or more commands or code on acomputer-readable recording medium and prompting a computer system toread and execute the one or more commands or code recorded onto therecording medium. Herein, the term “computer system” includes an OS, andhardware such as peripheral devices.

The operations described in the embodiments of the present invention maybe realized through programs. Programs that run on the terminal devices1 and the base station device 3 relating to the embodiments of thepresent invention are programs for controlling a CPU or the like(programs for prompting the functioning of a computer), so as to realizethe functions of the above-described embodiments relating to theembodiments of the present invention. The information handled by thesedevices is temporarily accumulated in RAM at the time of processing,then stored in various kinds of ROM or HDD, and when needed, read out,revised, or written by the CPU.

In addition to realizing the functions of the above-describedembodiments by executing programs, there are also cases where thefunctions of the embodiments of the present invention are realized bythe programs running cooperatively with an operating system, otherapplication programs, or the like in accordance with instructionsincluded in the programs.

The term “computer-readable recording medium” refers to semiconductormedia (e.g., RAM, nonvolatile memory cards, and the like), opticalrecording media (e.g, DVD, MO, MD, CD, BD, and the like), magnetic media(e.g., magnetic tape, flexible disks, and the like), and other suchportable media, a disk unit housed in a computer system, and other suchmemory devices. Furthermore, the term “computer-readable recordingmedium” is considered to include media dynamically holding a program forshort periods of time, such as a communication line used fortransmission of a program over a network such as the Internet, or via acommunication circuit such as a telephone circuit; or media holding aprogram for a given time, such as an internal nonvolatile memory of acomputer system serving as a server or client in such a case.

Furthermore, the program may be intended to realize some of thefunctions described above, and may further be capable of realizing thefunctions described above in combination with a program already recordedin the computer system.

The various function blocks or features of the terminal device 1 and thebase station device 3 used in the above-described embodiments may beimplemented or executed by an entity designed to execute the functionsdescribed herein, such as a general-purpose application processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC) or any general-purpose application integrated circuit(IC), a field programmable gate array signal (FPGA) or otherprogrammable logic device, a discrete gate or transistor logic, adiscrete hardware component, or a combination thereof.

The general-purpose application processor may be a microprocessor, orinstead, the processor may be a conventional type of processor,controller, microcontroller, or state machine. The general-purposeapplication processor, or the circuits mentioned above, may beconstituted of digital circuits or analog circuits.

The processor may be implemented by a combination of computing devices.For example, the processor is implemented by a DSP and a microprocessor,multiple microprocessors, one or more microprocessors connected to a DSPcore, or a combination of other such configurations.

While the embodiments of the present invention have been described indetail based on specific examples, the spirit of the embodiments and thescope of the claims of the present invention are clearly not limited tothese specific examples, and also include various design modificationsand the like not departing from the gist of the present invention. Inother words, the description herein is for the purpose of exemplarydescription, and does not impose any limitations on the embodiments ofthe present invention.

Furthermore, various modifications are possible within the scope of thepresent invention defined by the claims, and embodiments that are madeby suitably combining technical means disclosed according to thedifferent embodiments are also included in the technical scope of thepresent invention. Configurations in which elements described in theabove-described embodiments are replaced with ones having comparableeffect are also included in the technical scope of the present invention

DESCRIPTION OF REFERENCE NUMERALS

1, 1-1, 1-2, 1-3 Terminal device

3 Base station device

101, 201 Data generation part

103, 203 Transmission data storage part

105, 205 Transmission processing part

107, 207 Radio part

109, 209 Reception processing part

111, 211 MAC information extraction part

113, 213 Data processing part

115, 215 PHY control part

117, 217 MAC control part

119, 219 RRC control part

The invention claimed is:
 1. A terminal device comprising: receptioncircuitry configured to receive information indicating a number oftransmission repetitions for physical downlink control channel, andphysical layer control circuitry configured to perform radio linkmonitoring based on a plurality of thresholds each being defined as alevel of a downlink radio link, wherein a value of a first threshold ofthe plurality of thresholds is defined as a level at which the downlinkradio link cannot be reliably received, a value of a second threshold ofthe plurality of thresholds is defined as a level at which a downlinkradio link quality can be more reliably received than at the firstthreshold, each of the value of the first threshold and the value of thesecond threshold corresponds to a specific block error rate of aphysical downlink control channel transmission based on the number oftransmission repetitions.
 2. A base station device comprising: radioresource control circuitry configured to generate information indicatinga number of transmission repetitions for physical downlink controlchannel; and transmission circuitry configured to transmit, to aterminal device, the information indicating the number of transmissionrepetitions, wherein the radio link monitoring is performed based on aplurality of thresholds each being defined as a level of a downlinkradio link, a value of a first threshold of the plurality of thresholdsis defined as a level at which the downlink radio link cannot bereliably received, a value of a second threshold of the plurality ofthresholds is defined as a level at which a downlink radio link qualitycan be more reliably received than at the first threshold each of thevalue of the first threshold and the value of the second thresholdcorresponds to a specific block error rate of a physical downlinkcontrol channel transmission based on the number of transmissionrepetitions.
 3. A communication method for terminal device, thecommunication method comprising: receiving information indicating anumber of transmission repetitions for physical downlink controlchannel, and performing radio link monitoring based on a plurality ofthresholds each being defined as a level of a downlink radio link,wherein a value of a first threshold of the plurality of thresholds isdefined as a level at which the downlink radio link cannot be reliablyreceived, a value of a second threshold of the plurality of thresholdsis defined as a level at which a downlink radio link quality can be morereliably received than at the first threshold each of the value of thefirst threshold and the value of the second threshold corresponds to aspecific block error rate of a physical downlink control channeltransmission based on the number of transmission repetitions.
 4. Acommunication method for a base station device, the communication methodcomprising: generating information indicating a number of transmissionrepetitions for physical downlink control channel; and transmitting, toa terminal device, the information indicating the number of transmissionrepetitions, wherein the radio link monitoring is performed based on aplurality of thresholds each being defined as a level of a downlinkradio link, a value of a first threshold of the plurality of thresholdsis defined as a level at which the downlink radio link cannot bereliably received, a value of a second threshold of the plurality ofthresholds is defined as a level at which a downlink radio link qualitycan be more reliably received than at the first threshold each of thevalue of the first threshold and the value of the second thresholdcorresponds to a specific block error rate of a physical downlinkcontrol channel transmission based on the number of transmissionrepetitions.